feat: add AdminCouponsPage for coupon management

Full CRUD interface for coupons:
- Create, edit, delete coupons
- Three coupon types supported:
  - Single-Use: one-time redemption per user
  - Multi-Use Period: unlimited redemptions in timeframe (Wellpass)
  - Gift: bonus system coupons

Features:
- Auto-generate random coupon codes
- Configure tier, duration, validity period
- Set max redemptions (or unlimited)
- View redemption history per coupon (modal)
- Active/inactive state management
- Card-based layout with visual type indicators

Form improvements:
- Conditional fields based on coupon type
- Date pickers for period coupons
- Duration config for single-use/gift
- Help text for each field
- Labels above inputs (consistent with other pages)

Integrated in AdminPanel navigation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/App.jsx

@@ -23,6 +23,7 @@ import GuidePage      from './pages/GuidePage'
 import AdminTierLimitsPage from './pages/AdminTierLimitsPage'
 import AdminFeaturesPage from './pages/AdminFeaturesPage'
 import AdminTiersPage from './pages/AdminTiersPage'
+import AdminCouponsPage from './pages/AdminCouponsPage'
 import './app.css'
 
 function Nav() {
@@ -121,6 +122,7 @@ function AppShell() {
           <Route path="/admin/tier-limits" element={<AdminTierLimitsPage/>}/>
           <Route path="/admin/features" element={<AdminFeaturesPage/>}/>
           <Route path="/admin/tiers" element={<AdminTiersPage/>}/>
+          <Route path="/admin/coupons" element={<AdminCouponsPage/>}/>
         </Routes>
       </main>
       <Nav/>

frontend/src/pages/AdminCouponsPage.jsx

@@ -0,0 +1,523 @@
+import { useState, useEffect } from 'react'
+import { Save, Plus, Edit2, Trash2, X, Eye, Gift, Ticket } from 'lucide-react'
+import { api } from '../utils/api'
+
+export default function AdminCouponsPage() {
+  const [loading, setLoading] = useState(true)
+  const [error, setError] = useState('')
+  const [success, setSuccess] = useState('')
+  const [coupons, setCoupons] = useState([])
+  const [editingId, setEditingId] = useState(null)
+  const [showAddForm, setShowAddForm] = useState(false)
+  const [viewingRedemptions, setViewingRedemptions] = useState(null)
+  const [redemptions, setRedemptions] = useState([])
+  const [formData, setFormData] = useState({
+    code: '',
+    type: 'single_use',
+    valid_from: '',
+    valid_until: '',
+    grants_tier: 'premium',
+    duration_days: 30,
+    max_redemptions: 1,
+    notes: '',
+    active: true
+  })
+
+  useEffect(() => {
+    loadCoupons()
+  }, [])
+
+  async function loadCoupons() {
+    try {
+      setLoading(true)
+      const data = await api.listCoupons()
+      setCoupons(data)
+      setError('')
+    } catch (e) {
+      setError(e.message)
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  async function loadRedemptions(couponId) {
+    try {
+      const data = await api.getCouponRedemptions(couponId)
+      setRedemptions(data)
+      setViewingRedemptions(couponId)
+    } catch (e) {
+      setError(e.message)
+    }
+  }
+
+  function resetForm() {
+    setFormData({
+      code: '',
+      type: 'single_use',
+      valid_from: '',
+      valid_until: '',
+      grants_tier: 'premium',
+      duration_days: 30,
+      max_redemptions: 1,
+      notes: '',
+      active: true
+    })
+    setEditingId(null)
+    setShowAddForm(false)
+  }
+
+  function startEdit(coupon) {
+    setFormData({
+      code: coupon.code,
+      type: coupon.type,
+      valid_from: coupon.valid_from ? coupon.valid_from.split('T')[0] : '',
+      valid_until: coupon.valid_until ? coupon.valid_until.split('T')[0] : '',
+      grants_tier: coupon.grants_tier,
+      duration_days: coupon.duration_days || 30,
+      max_redemptions: coupon.max_redemptions || 1,
+      notes: coupon.notes || '',
+      active: coupon.active
+    })
+    setEditingId(coupon.id)
+    setShowAddForm(false)
+  }
+
+  function startAdd() {
+    // Generate random code
+    const randomCode = `${formData.type === 'gift' ? 'GIFT' : 'PROMO'}-${Math.random().toString(36).substr(2, 8).toUpperCase()}`
+    setFormData({ ...formData, code: randomCode })
+    setShowAddForm(true)
+    setEditingId(null)
+  }
+
+  async function handleSave() {
+    try {
+      setError('')
+      setSuccess('')
+
+      if (!formData.code.trim()) {
+        setError('Code erforderlich')
+        return
+      }
+
+      const payload = {
+        code: formData.code.trim().toUpperCase(),
+        type: formData.type,
+        valid_from: formData.valid_from || null,
+        valid_until: formData.valid_until || null,
+        grants_tier: formData.grants_tier,
+        duration_days: parseInt(formData.duration_days) || null,
+        max_redemptions: formData.type === 'single_use' ? 1 : (parseInt(formData.max_redemptions) || null),
+        notes: formData.notes.trim(),
+        active: formData.active
+      }
+
+      if (editingId) {
+        await api.updateCoupon(editingId, payload)
+        setSuccess('Coupon aktualisiert')
+      } else {
+        await api.createCoupon(payload)
+        setSuccess('Coupon erstellt')
+      }
+
+      await loadCoupons()
+      resetForm()
+    } catch (e) {
+      setError(e.message)
+    }
+  }
+
+  async function handleDelete(couponId) {
+    if (!confirm('Coupon wirklich löschen?')) return
+    try {
+      setError('')
+      await api.deleteCoupon(couponId)
+      setSuccess('Coupon gelöscht')
+      await loadCoupons()
+    } catch (e) {
+      setError(e.message)
+    }
+  }
+
+  function formatDate(dateStr) {
+    if (!dateStr) return '-'
+    return new Date(dateStr).toLocaleDateString('de-DE')
+  }
+
+  if (loading) return (
+    <div style={{ display: 'flex', justifyContent: 'center', padding: 40 }}>
+      <div className="spinner" />
+    </div>
+  )
+
+  const couponTypes = [
+    { value: 'single_use', label: 'Single-Use (einmalig)', icon: '🎟️' },
+    { value: 'multi_use_period', label: 'Multi-Use Period (Zeitraum)', icon: '🔄' },
+    { value: 'gift', label: 'Geschenk-Coupon', icon: '🎁' }
+  ]
+
+  const tierOptions = [
+    { value: 'free', label: 'Free' },
+    { value: 'basic', label: 'Basic' },
+    { value: 'premium', label: 'Premium' }
+  ]
+
+  return (
+    <div style={{ paddingBottom: 80 }}>
+      {/* Header */}
+      <div style={{
+        display: 'flex', alignItems: 'center', justifyContent: 'space-between',
+        marginBottom: 20
+      }}>
+        <div>
+          <div style={{ fontSize: 20, fontWeight: 700, color: 'var(--text1)' }}>
+            Coupon-Verwaltung
+          </div>
+          <div style={{ fontSize: 13, color: 'var(--text3)', marginTop: 4 }}>
+            Trial-Codes, Wellpass-Integration, Geschenk-Coupons
+          </div>
+        </div>
+        {!showAddForm && !editingId && (
+          <button className="btn btn-primary" onClick={startAdd}>
+            <Plus size={16} /> Neuer Coupon
+          </button>
+        )}
+      </div>
+
+      {/* Messages */}
+      {error && (
+        <div style={{
+          padding: 12, background: 'var(--danger)', color: 'white',
+          borderRadius: 8, marginBottom: 16, fontSize: 14
+        }}>
+          {error}
+        </div>
+      )}
+      {success && (
+        <div style={{
+          padding: 12, background: 'var(--accent)', color: 'white',
+          borderRadius: 8, marginBottom: 16, fontSize: 14
+        }}>
+          {success}
+        </div>
+      )}
+
+      {/* Add/Edit Form */}
+      {(showAddForm || editingId) && (
+        <div className="card" style={{ padding: 20, marginBottom: 20 }}>
+          <div style={{
+            display: 'flex', alignItems: 'center', justifyContent: 'space-between',
+            marginBottom: 16
+          }}>
+            <div style={{ fontSize: 16, fontWeight: 600 }}>
+              {editingId ? 'Coupon bearbeiten' : 'Neuer Coupon'}
+            </div>
+            <button
+              className="btn btn-secondary"
+              onClick={resetForm}
+              style={{ padding: '6px 12px' }}
+            >
+              <X size={16} />
+            </button>
+          </div>
+
+          <div style={{ display: 'grid', gap: 16 }}>
+            {/* Code */}
+            <div>
+              <label className="form-label" style={{ display: 'block', marginBottom: 6 }}>
+                Coupon-Code *
+              </label>
+              <input
+                className="form-input"
+                style={{ width: '100%', fontFamily: 'monospace', textTransform: 'uppercase' }}
+                value={formData.code}
+                onChange={(e) => setFormData({ ...formData, code: e.target.value })}
+                placeholder="Z.B. PROMO-2026"
+              />
+              <div style={{ fontSize: 11, color: 'var(--text3)', marginTop: 4 }}>
+                Wird automatisch in Großbuchstaben konvertiert
+              </div>
+            </div>
+
+            {/* Type */}
+            <div>
+              <label className="form-label" style={{ display: 'block', marginBottom: 6 }}>
+                Coupon-Typ
+              </label>
+              <select
+                className="form-input"
+                style={{ width: '100%' }}
+                value={formData.type}
+                onChange={(e) => setFormData({ ...formData, type: e.target.value })}
+              >
+                {couponTypes.map(t => (
+                  <option key={t.value} value={t.value}>
+                    {t.icon} {t.label}
+                  </option>
+                ))}
+              </select>
+              <div style={{ fontSize: 11, color: 'var(--text3)', marginTop: 4 }}>
+                {formData.type === 'single_use' && 'Kann nur einmal pro User eingelöst werden'}
+                {formData.type === 'multi_use_period' && 'Unbegrenzte Einlösungen im Gültigkeitszeitraum (z.B. Wellpass)'}
+                {formData.type === 'gift' && 'Geschenk-Coupon für Bonus-System'}
+              </div>
+            </div>
+
+            {/* Tier */}
+            <div>
+              <label className="form-label" style={{ display: 'block', marginBottom: 6 }}>
+                Gewährt Tier
+              </label>
+              <select
+                className="form-input"
+                style={{ width: '100%' }}
+                value={formData.grants_tier}
+                onChange={(e) => setFormData({ ...formData, grants_tier: e.target.value })}
+              >
+                {tierOptions.map(t => (
+                  <option key={t.value} value={t.value}>{t.label}</option>
+                ))}
+              </select>
+            </div>
+
+            {/* Duration (only for single_use and gift) */}
+            {(formData.type === 'single_use' || formData.type === 'gift') && (
+              <div>
+                <label className="form-label" style={{ display: 'block', marginBottom: 6 }}>
+                  Gültigkeitsdauer (Tage)
+                </label>
+                <input
+                  className="form-input"
+                  style={{ width: '100%' }}
+                  type="number"
+                  value={formData.duration_days}
+                  onChange={(e) => setFormData({ ...formData, duration_days: e.target.value })}
+                />
+                <div style={{ fontSize: 11, color: 'var(--text3)', marginTop: 4 }}>
+                  Wie lange ist der gewährte Zugriff gültig?
+                </div>
+              </div>
+            )}
+
+            {/* Valid From/Until (for multi_use_period) */}
+            {formData.type === 'multi_use_period' && (
+              <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
+                <div>
+                  <label className="form-label" style={{ display: 'block', marginBottom: 6 }}>
+                    Gültig ab
+                  </label>
+                  <input
+                    className="form-input"
+                    style={{ width: '100%' }}
+                    type="date"
+                    value={formData.valid_from}
+                    onChange={(e) => setFormData({ ...formData, valid_from: e.target.value })}
+                  />
+                </div>
+                <div>
+                  <label className="form-label" style={{ display: 'block', marginBottom: 6 }}>
+                    Gültig bis
+                  </label>
+                  <input
+                    className="form-input"
+                    style={{ width: '100%' }}
+                    type="date"
+                    value={formData.valid_until}
+                    onChange={(e) => setFormData({ ...formData, valid_until: e.target.value })}
+                  />
+                </div>
+              </div>
+            )}
+
+            {/* Max Redemptions (not for single_use) */}
+            {formData.type !== 'single_use' && (
+              <div>
+                <label className="form-label" style={{ display: 'block', marginBottom: 6 }}>
+                  Maximale Einlösungen (optional)
+                </label>
+                <input
+                  className="form-input"
+                  style={{ width: '100%' }}
+                  type="number"
+                  value={formData.max_redemptions}
+                  onChange={(e) => setFormData({ ...formData, max_redemptions: e.target.value })}
+                  placeholder="Leer = unbegrenzt"
+                />
+              </div>
+            )}
+
+            {/* Notes */}
+            <div>
+              <label className="form-label" style={{ display: 'block', marginBottom: 6 }}>
+                Notizen (optional)
+              </label>
+              <input
+                className="form-input"
+                style={{ width: '100%' }}
+                value={formData.notes}
+                onChange={(e) => setFormData({ ...formData, notes: e.target.value })}
+                placeholder="Z.B. 'Für Marketing-Kampagne März 2026'"
+              />
+            </div>
+
+            {/* Active */}
+            <div>
+              <label style={{ display: 'flex', alignItems: 'center', gap: 6, fontSize: 13 }}>
+                <input
+                  type="checkbox"
+                  checked={formData.active}
+                  onChange={(e) => setFormData({ ...formData, active: e.target.checked })}
+                />
+                Coupon aktiviert (kann eingelöst werden)
+              </label>
+            </div>
+
+            {/* Actions */}
+            <div style={{ display: 'flex', gap: 8, marginTop: 8 }}>
+              <button className="btn btn-primary" onClick={handleSave}>
+                <Save size={14} /> {editingId ? 'Aktualisieren' : 'Erstellen'}
+              </button>
+              <button className="btn btn-secondary" onClick={resetForm}>
+                Abbrechen
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
+
+      {/* Redemptions Modal */}
+      {viewingRedemptions && (
+        <div style={{
+          position: 'fixed', top: 0, left: 0, right: 0, bottom: 0,
+          background: 'rgba(0,0,0,0.5)', zIndex: 1000,
+          display: 'flex', alignItems: 'center', justifyContent: 'center',
+          padding: 20
+        }} onClick={() => setViewingRedemptions(null)}>
+          <div className="card" style={{ padding: 20, maxWidth: 600, width: '100%', maxHeight: '80vh', overflow: 'auto' }}
+            onClick={(e) => e.stopPropagation()}>
+            <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', marginBottom: 16 }}>
+              <div style={{ fontSize: 16, fontWeight: 600 }}>Einlösungen</div>
+              <button className="btn btn-secondary" onClick={() => setViewingRedemptions(null)} style={{ padding: '6px 12px' }}>
+                <X size={16} />
+              </button>
+            </div>
+
+            {redemptions.length === 0 ? (
+              <div style={{ textAlign: 'center', padding: 40, color: 'var(--text3)' }}>
+                Noch keine Einlösungen
+              </div>
+            ) : (
+              <div style={{ display: 'grid', gap: 8 }}>
+                {redemptions.map(r => (
+                  <div key={r.id} className="card" style={{ padding: 12, background: 'var(--surface)' }}>
+                    <div style={{ fontWeight: 500 }}>{r.profile_name || `User #${r.profile_id}`}</div>
+                    <div style={{ fontSize: 12, color: 'var(--text3)', marginTop: 2 }}>
+                      Eingelöst am {formatDate(r.redeemed_at)}
+                    </div>
+                  </div>
+                ))}
+              </div>
+            )}
+          </div>
+        </div>
+      )}
+
+      {/* Coupons List */}
+      <div style={{ display: 'grid', gap: 12 }}>
+        {coupons.length === 0 && (
+          <div className="card" style={{ padding: 40, textAlign: 'center', color: 'var(--text3)' }}>
+            Keine Coupons vorhanden
+          </div>
+        )}
+        {coupons.map(coupon => (
+          <div
+            key={coupon.id}
+            className="card"
+            style={{
+              padding: 16,
+              opacity: coupon.active ? 1 : 0.6,
+              border: coupon.active ? '1px solid var(--border)' : '1px dashed var(--border)'
+            }}
+          >
+            <div style={{ display: 'flex', alignItems: 'flex-start', justifyContent: 'space-between', gap: 12 }}>
+              <div style={{ flex: 1 }}>
+                <div style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 4 }}>
+                  <div style={{
+                    fontSize: 16, fontWeight: 700, color: 'var(--text1)',
+                    fontFamily: 'monospace', background: 'var(--surface2)',
+                    padding: '4px 8px', borderRadius: 4
+                  }}>
+                    {coupon.code}
+                  </div>
+                  <span style={{
+                    padding: '2px 8px', borderRadius: 4, fontSize: 11,
+                    background: 'var(--accent-light)', color: 'var(--accent-dark)', fontWeight: 600
+                  }}>
+                    {couponTypes.find(t => t.value === coupon.type)?.icon} {couponTypes.find(t => t.value === coupon.type)?.label}
+                  </span>
+                  {!coupon.active && (
+                    <span style={{
+                      padding: '2px 8px', borderRadius: 4, fontSize: 10,
+                      background: 'var(--danger)', color: 'white', fontWeight: 600
+                    }}>
+                      INAKTIV
+                    </span>
+                  )}
+                </div>
+
+                <div style={{ fontSize: 13, color: 'var(--text2)', marginBottom: 8 }}>
+                  Gewährt: <strong>{coupon.grants_tier}</strong>
+                  {coupon.duration_days && ` für ${coupon.duration_days} Tage`}
+                </div>
+
+                {coupon.notes && (
+                  <div style={{ fontSize: 12, color: 'var(--text3)', marginBottom: 8 }}>
+                    📝 {coupon.notes}
+                  </div>
+                )}
+
+                <div style={{ display: 'flex', gap: 16, fontSize: 12, color: 'var(--text3)' }}>
+                  {coupon.valid_from && (
+                    <div><strong>Gültig ab:</strong> {formatDate(coupon.valid_from)}</div>
+                  )}
+                  {coupon.valid_until && (
+                    <div><strong>Gültig bis:</strong> {formatDate(coupon.valid_until)}</div>
+                  )}
+                  <div>
+                    <strong>Einlösungen:</strong> {coupon.current_redemptions || 0}
+                    {coupon.max_redemptions ? ` / ${coupon.max_redemptions}` : ' / ∞'}
+                  </div>
+                </div>
+              </div>
+
+              <div style={{ display: 'flex', gap: 4, flexShrink: 0 }}>
+                <button
+                  className="btn btn-secondary"
+                  onClick={() => loadRedemptions(coupon.id)}
+                  style={{ padding: '6px 12px', fontSize: 12 }}
+                  title="Einlösungen anzeigen"
+                >
+                  <Eye size={14} />
+                </button>
+                <button
+                  className="btn btn-secondary"
+                  onClick={() => startEdit(coupon)}
+                  style={{ padding: '6px 12px', fontSize: 12 }}
+                >
+                  <Edit2 size={14} />
+                </button>
+                <button
+                  className="btn btn-secondary"
+                  onClick={() => handleDelete(coupon.id)}
+                  style={{ padding: '6px 12px', fontSize: 12, color: 'var(--danger)' }}
+                >
+                  <Trash2 size={14} />
+                </button>
+              </div>
+            </div>
+          </div>
+        ))}
+      </div>
+    </div>
+  )
+}

frontend/src/pages/AdminPanel.jsx

@@ -423,6 +423,11 @@ export default function AdminPanel() {
               📊 Tier Limits Matrix bearbeiten
             </button>
           </Link>
+          <Link to="/admin/coupons">
+            <button className="btn btn-secondary btn-full">
+              🎟️ Coupons verwalten
+            </button>
+          </Link>
         </div>
       </div>
     </div>