feat: Focus Areas Slider UI (Goal System v2.0 complete)

Replaces single goal mode cards with weighted multi-focus system

UI Features:
- 6 sliders for focus dimensions (5% increments)
- Live sum calculation with visual feedback
- Validation: Sum must equal 100%
- Color-coded sliders per dimension
- Edit/Display mode toggle
- Shows derived values if not customized

UX Flow:
1. Default: Shows focus distribution (bars)
2. Click 'Anpassen': Shows sliders
3. Adjust percentages (sum = 100%)
4. Save → Updates backend + reloads

Visual:
- Active dimensions shown as colored cards (display mode)
- Gradient sliders with percentage labels (edit mode)
- Green box when sum = 100%, red when != 100%
- Info message if derived from old goal_mode

Complete v2.0:
✅ Backend (Migration 027, API, get_focus_weights V2)
✅ Frontend (Slider UI, state management, validation)
✅ Auto-migration (goal_mode → focus_areas)

Ready for: KI-Integration with weighted scoring

frontend/src/pages/GoalsPage.jsx

@@ -46,6 +46,16 @@ const GOAL_MODES = [
 
 export default function GoalsPage() {
   const [goalMode, setGoalMode] = useState(null)
+  const [focusAreas, setFocusAreas] = useState(null)
+  const [focusEditing, setFocusEditing] = useState(false)
+  const [focusTemp, setFocusTemp] = useState({
+    weight_loss_pct: 0,
+    muscle_gain_pct: 0,
+    strength_pct: 0,
+    endurance_pct: 0,
+    flexibility_pct: 0,
+    health_pct: 0
+  })
   const [goals, setGoals] = useState([])
   const [goalTypes, setGoalTypes] = useState([]) // Dynamic from DB (Phase 1.5)
   const [goalTypesMap, setGoalTypesMap] = useState({}) // For quick lookup
@@ -74,13 +84,16 @@ export default function GoalsPage() {
     setLoading(true)
     setError(null)
     try {
-      const [modeData, goalsData, typesData] = await Promise.all([
+      const [modeData, goalsData, typesData, focusData] = await Promise.all([
         api.getGoalMode(),
         api.listGoals(),
-        api.listGoalTypeDefinitions() // Phase 1.5: Load from DB
+        api.listGoalTypeDefinitions(), // Phase 1.5: Load from DB
+        api.getFocusAreas() // v2.0: Load focus areas
       ])
       setGoalMode(modeData.goal_mode)
       setGoals(goalsData)
+      setFocusAreas(focusData)
+      setFocusTemp(focusData) // Initialize temp state
 
       // Convert types array to map for quick lookup
       const typesMap = {}
@@ -258,43 +271,189 @@ export default function GoalsPage() {
         </div>
       )}
 
-      {/* Strategic Goal Mode Selection */}
+      {/* Focus Areas (v2.0) */}
       <div className="card" style={{ marginBottom: 16 }}>
-        <h2 style={{ marginTop: 0 }}>🎯 Trainingsmodus</h2>
+        <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 8 }}>
+          <h2 style={{ margin: 0 }}>🎯 Fokus-Bereiche</h2>
+          {!focusEditing && focusAreas && (
+            <button
+              className="btn-secondary"
+              onClick={() => setFocusEditing(true)}
+              style={{ padding: '6px 12px' }}
+            >
+              <Pencil size={14} /> Anpassen
+            </button>
+          )}
+        </div>
         <p style={{ color: 'var(--text2)', fontSize: 14, marginBottom: 16 }}>
-          Wähle deine grundlegende Trainingsausrichtung. Dies beeinflusst die Gewichtung
+          Gewichte deine Trainingsziele individuell. Die Summe muss 100% ergeben.
-          und Interpretation aller Analysen.
+          {focusAreas && !focusAreas.custom && (
+            <span style={{ display: 'block', marginTop: 4, fontStyle: 'italic' }}>
+              ℹ️ Aktuell abgeleitet aus Trainingsmodus "{goalMode}" - klicke "Anpassen" für individuelle Gewichtung
+            </span>
+          )}
         </p>
 
-        <div style={{
+        {focusEditing ? (
-          display: 'grid',
+          <>
-          gridTemplateColumns: 'repeat(auto-fit, minmax(200px, 1fr))',
+            {/* Sliders */}
-          gap: 12
+            <div style={{ display: 'flex', flexDirection: 'column', gap: 20, marginBottom: 20 }}>
-        }}>
+              {[
-          {GOAL_MODES.map(mode => (
+                { key: 'weight_loss_pct', label: 'Fettabbau', icon: '📉', color: '#D85A30' },
-            <button
+                { key: 'muscle_gain_pct', label: 'Muskelaufbau', icon: '💪', color: '#378ADD' },
-              key={mode.id}
+                { key: 'strength_pct', label: 'Kraftsteigerung', icon: '🏋️', color: '#7B68EE' },
-              onClick={() => handleGoalModeChange(mode.id)}
+                { key: 'endurance_pct', label: 'Ausdauer', icon: '🏃', color: '#1D9E75' },
-              className={goalMode === mode.id ? 'btn-primary' : 'btn-secondary'}
+                { key: 'flexibility_pct', label: 'Beweglichkeit', icon: '🤸', color: '#E67E22' },
-              style={{
+                { key: 'health_pct', label: 'Gesundheit', icon: '❤️', color: '#F59E0B' }
-                padding: 16,
+              ].map(area => (
-                textAlign: 'left',
+                <div key={area.key}>
-                background: goalMode === mode.id ? mode.color : 'var(--surface)',
+                  <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 8 }}>
-                borderColor: goalMode === mode.id ? mode.color : 'var(--border)',
+                    <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
-                color: goalMode === mode.id ? 'white' : 'var(--text1)'
+                      <span style={{ fontSize: 20 }}>{area.icon}</span>
-              }}
+                      <span style={{ fontWeight: 500 }}>{area.label}</span>
-            >
+                    </div>
-              <div style={{ fontSize: 24, marginBottom: 8 }}>{mode.icon}</div>
+                    <span style={{
-              <div style={{ fontWeight: 600, marginBottom: 4 }}>{mode.label}</div>
+                      fontSize: 18,
-              <div style={{
+                      fontWeight: 600,
-                fontSize: 12,
+                      color: area.color,
-                opacity: goalMode === mode.id ? 0.9 : 0.7
+                      minWidth: 50,
-              }}>
+                      textAlign: 'right'
-                {mode.description}
+                    }}>
+                      {focusTemp[area.key]}%
+                    </span>
+                  </div>
+                  <input
+                    type="range"
+                    min="0"
+                    max="100"
+                    step="5"
+                    value={focusTemp[area.key]}
+                    onChange={e => setFocusTemp(f => ({ ...f, [area.key]: parseInt(e.target.value) }))}
+                    style={{
+                      width: '100%',
+                      height: 8,
+                      borderRadius: 4,
+                      background: `linear-gradient(to right, ${area.color} 0%, ${area.color} ${focusTemp[area.key]}%, var(--border) ${focusTemp[area.key]}%, var(--border) 100%)`,
+                      outline: 'none',
+                      cursor: 'pointer'
+                    }}
+                  />
+                </div>
+              ))}
+            </div>
+
+            {/* Sum Display */}
+            <div style={{
+              padding: 12,
+              background: (() => {
+                const sum = Object.values(focusTemp).reduce((a, b) => a + b, 0)
+                if (sum === 100) return 'var(--accent)'
+                return '#FEF2F2'
+              })(),
+              border: (() => {
+                const sum = Object.values(focusTemp).reduce((a, b) => a + b, 0)
+                if (sum === 100) return '1px solid var(--accent)'
+                return '1px solid #FCA5A5'
+              })(),
+              borderRadius: 8,
+              marginBottom: 16
+            }}>
+              <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center' }}>
+                <span style={{
+                  fontWeight: 600,
+                  color: (() => {
+                    const sum = Object.values(focusTemp).reduce((a, b) => a + b, 0)
+                    if (sum === 100) return 'white'
+                    return '#DC2626'
+                  })()
+                }}>
+                  Summe:
+                </span>
+                <span style={{
+                  fontSize: 20,
+                  fontWeight: 700,
+                  color: (() => {
+                    const sum = Object.values(focusTemp).reduce((a, b) => a + b, 0)
+                    if (sum === 100) return 'white'
+                    return '#DC2626'
+                  })()
+                }}>
+                  {Object.values(focusTemp).reduce((a, b) => a + b, 0)}%
+                </span>
               </div>
-            </button>
+              {Object.values(focusTemp).reduce((a, b) => a + b, 0) !== 100 && (
-          ))}
+                <div style={{ fontSize: 12, marginTop: 4, color: '#DC2626' }}>
-        </div>
+                  ⚠️ Summe muss 100% ergeben
+                </div>
+              )}
+            </div>
+
+            {/* Action Buttons */}
+            <div style={{ display: 'flex', gap: 12 }}>
+              <button
+                className="btn-primary"
+                onClick={async () => {
+                  const sum = Object.values(focusTemp).reduce((a, b) => a + b, 0)
+                  if (sum !== 100) {
+                    setError('Summe muss 100% ergeben')
+                    return
+                  }
+                  try {
+                    await api.updateFocusAreas(focusTemp)
+                    showToast('✓ Fokus-Bereiche aktualisiert')
+                    await loadData()
+                    setFocusEditing(false)
+                    setError(null)
+                  } catch (err) {
+                    setError(err.message || 'Fehler beim Speichern')
+                  }
+                }}
+                disabled={Object.values(focusTemp).reduce((a, b) => a + b, 0) !== 100}
+                style={{ flex: 1 }}
+              >
+                Speichern
+              </button>
+              <button
+                className="btn-secondary"
+                onClick={() => {
+                  setFocusTemp(focusAreas)
+                  setFocusEditing(false)
+                  setError(null)
+                }}
+                style={{ flex: 1 }}
+              >
+                Abbrechen
+              </button>
+            </div>
+          </>
+        ) : focusAreas && (
+          /* Display Mode */
+          <div style={{ display: 'grid', gridTemplateColumns: 'repeat(auto-fit, minmax(150px, 1fr))', gap: 12 }}>
+            {[
+              { key: 'weight_loss_pct', label: 'Fettabbau', icon: '📉', color: '#D85A30' },
+              { key: 'muscle_gain_pct', label: 'Muskelaufbau', icon: '💪', color: '#378ADD' },
+              { key: 'strength_pct', label: 'Kraftsteigerung', icon: '🏋️', color: '#7B68EE' },
+              { key: 'endurance_pct', label: 'Ausdauer', icon: '🏃', color: '#1D9E75' },
+              { key: 'flexibility_pct', label: 'Beweglichkeit', icon: '🤸', color: '#E67E22' },
+              { key: 'health_pct', label: 'Gesundheit', icon: '❤️', color: '#F59E0B' }
+            ].filter(area => focusAreas[area.key] > 0).map(area => (
+              <div
+                key={area.key}
+                style={{
+                  padding: 12,
+                  background: 'var(--surface2)',
+                  border: '1px solid var(--border)',
+                  borderRadius: 8,
+                  textAlign: 'center'
+                }}
+              >
+                <div style={{ fontSize: 24, marginBottom: 4 }}>{area.icon}</div>
+                <div style={{ fontSize: 12, color: 'var(--text2)', marginBottom: 4 }}>{area.label}</div>
+                <div style={{ fontSize: 20, fontWeight: 700, color: area.color }}>{focusAreas[area.key]}%</div>
+              </div>
+            ))}
+          </div>
+        )}
       </div>
 
       {/* Tactical Goals List */}