feat: resend verification email functionality

Backend:
- Added POST /api/auth/resend-verification endpoint
- Rate limited to 3/hour to prevent abuse
- Generates new verification token (24h validity)
- Sends new verification email

Frontend:
- Verify.jsx: Added "expired" status with resend flow
- Email input + "Neue Bestätigungs-E-Mail senden" button
- EmailVerificationBanner: Added "Neue E-Mail senden" button
- Shows success/error feedback inline
- api.js: Added resendVerification() helper

User flows:
1. Expired token → Verify page shows resend form
2. Email lost → Dashboard banner has resend button
3. Both flows use same backend endpoint

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

backend/routers/auth.py

@@ -323,3 +323,74 @@ async def verify_email(token: str):
             "email": prof['email']
         }
     }
+
+
+@router.post("/resend-verification")
+@limiter.limit("3/hour")
+async def resend_verification(req: dict, request: Request):
+    """Resend verification email for unverified account."""
+    email = req.get('email', '').strip().lower()
+
+    if not email:
+        raise HTTPException(400, "E-Mail-Adresse erforderlich")
+
+    with get_db() as conn:
+        cur = get_cursor(conn)
+
+        # Find profile by email
+        cur.execute("""
+            SELECT id, name, email, email_verified, verification_token, verification_expires
+            FROM profiles
+            WHERE email=%s
+        """, (email,))
+
+        prof = cur.fetchone()
+
+        if not prof:
+            # Don't leak info about existing emails
+            return {"ok": True, "message": "Falls ein Account mit dieser E-Mail existiert, wurde eine Bestätigungs-E-Mail versendet."}
+
+        if prof['email_verified']:
+            raise HTTPException(400, "E-Mail-Adresse bereits bestätigt")
+
+        # Generate new verification token
+        verification_token = secrets.token_urlsafe(32)
+        verification_expires = datetime.now(timezone.utc) + timedelta(hours=24)
+
+        cur.execute("""
+            UPDATE profiles
+            SET verification_token=%s, verification_expires=%s
+            WHERE id=%s
+        """, (verification_token, verification_expires, prof['id']))
+
+    # Send verification email
+    app_url = os.getenv("APP_URL", "https://mitai.jinkendo.de")
+    verify_url = f"{app_url}/verify?token={verification_token}"
+
+    email_body = f"""Hallo {prof['name']},
+
+du hast eine neue Bestätigungs-E-Mail angefordert.
+
+Bitte bestätige deine E-Mail-Adresse, indem du auf folgenden Link klickst:
+
+{verify_url}
+
+Dieser Link ist 24 Stunden gültig.
+
+Falls du diese E-Mail nicht angefordert hast, kannst du sie einfach ignorieren.
+
+Viele Grüße
+Dein Mitai Jinkendo Team
+"""
+
+    try:
+        send_email(
+            to=email,
+            subject="Neue Bestätigungs-E-Mail - Mitai Jinkendo",
+            body=email_body
+        )
+    except Exception as e:
+        print(f"Failed to send verification email: {e}")
+        raise HTTPException(500, "E-Mail konnte nicht versendet werden")
+
+    return {"ok": True, "message": "Bestätigungs-E-Mail wurde erneut versendet."}

frontend/src/components/EmailVerificationBanner.jsx

@@ -1,7 +1,33 @@
+import { useState } from 'react'
+import { api } from '../utils/api'
+
 export default function EmailVerificationBanner({ profile }) {
+  const [resending, setResending] = useState(false)
+  const [success, setSuccess] = useState(false)
+  const [error, setError] = useState(null)
+
   // Only show if email is not verified
   if (!profile || profile.email_verified !== false) return null
 
+  const handleResend = async () => {
+    if (!profile.email) return
+
+    setResending(true)
+    setError(null)
+    setSuccess(false)
+
+    try {
+      await api.resendVerification(profile.email)
+      setSuccess(true)
+      setTimeout(() => setSuccess(false), 5000)
+    } catch (err) {
+      setError(err.message || 'Fehler beim Versenden')
+      setTimeout(() => setError(null), 5000)
+    } finally {
+      setResending(false)
+    }
+  }
+
   return (
     <div style={{
       background: '#FFF4E6',
@@ -11,7 +37,8 @@ export default function EmailVerificationBanner({ profile }) {
       marginBottom: 20,
       display: 'flex',
       alignItems: 'center',
-      gap: 16
+      gap: 16,
+      flexWrap: 'wrap'
     }}>
       <div style={{
         fontSize: 32,
@@ -19,7 +46,7 @@ export default function EmailVerificationBanner({ profile }) {
       }}>
         📧
       </div>
-      <div style={{flex: 1}}>
+      <div style={{flex: 1, minWidth: 200}}>
         <div style={{
           fontWeight: 700,
           fontSize: 15,
@@ -34,9 +61,36 @@ export default function EmailVerificationBanner({ profile }) {
           lineHeight: 1.4
         }}>
           Bitte prüfe dein Postfach und klicke auf den Bestätigungslink.
-          Ohne Bestätigung ist dein Account eingeschränkt.
+          {success && (
+            <span style={{color:'var(--accent)', fontWeight:600, marginLeft:4}}>
+              ✓ Neue E-Mail versendet!
+            </span>
+          )}
+          {error && (
+            <span style={{color:'var(--danger)', fontWeight:600, marginLeft:4}}>
+              ✗ {error}
+            </span>
+          )}
         </div>
       </div>
+      <button
+        onClick={handleResend}
+        disabled={resending || success}
+        style={{
+          padding: '8px 16px',
+          borderRadius: 8,
+          background: success ? 'var(--accent)' : '#F59E0B',
+          color: 'white',
+          fontWeight: 600,
+          fontSize: 13,
+          border: 'none',
+          cursor: resending || success ? 'not-allowed' : 'pointer',
+          whiteSpace: 'nowrap',
+          opacity: resending || success ? 0.6 : 1
+        }}
+      >
+        {resending ? 'Sende...' : success ? '✓ Versendet' : 'Neue E-Mail senden'}
+      </button>
     </div>
   )
 }

frontend/src/pages/Verify.jsx

@@ -9,8 +9,11 @@ export default function Verify() {
   const navigate = useNavigate()
   const { login } = useAuth()
 
-  const [status, setStatus] = useState('loading') // loading | success | error
+  const [status, setStatus] = useState('loading') // loading | success | error | expired
   const [error, setError] = useState(null)
+  const [email, setEmail] = useState('')
+  const [resending, setResending] = useState(false)
+  const [resendSuccess, setResendSuccess] = useState(false)
 
   useEffect(() => {
     const verify = async () => {
@@ -37,14 +40,41 @@ export default function Verify() {
           setError('Verifizierung erfolgreich, aber Login fehlgeschlagen')
         }
       } catch (err) {
+        const errorMsg = err.message || 'Verifizierung fehlgeschlagen'
+
+        // Check if token expired
+        if (errorMsg.includes('abgelaufen') || errorMsg.includes('expired')) {
+          setStatus('expired')
+          setError(errorMsg)
+        } else {
           setStatus('error')
-        setError(err.message || 'Verifizierung fehlgeschlagen')
+          setError(errorMsg)
+        }
       }
     }
 
     verify()
   }, [token, login, navigate])
 
+  const handleResend = async () => {
+    if (!email.trim()) {
+      setError('Bitte E-Mail-Adresse eingeben')
+      return
+    }
+
+    setResending(true)
+    setError(null)
+
+    try {
+      await api.resendVerification(email.trim().toLowerCase())
+      setResendSuccess(true)
+    } catch (err) {
+      setError(err.message || 'E-Mail konnte nicht versendet werden')
+    } finally {
+      setResending(false)
+    }
+  }
+
   if (status === 'loading') {
     return (
       <div style={{
@@ -58,6 +88,95 @@ export default function Verify() {
     )
   }
 
+  if (status === 'expired') {
+    return (
+      <div style={{
+        maxWidth:420, margin:'0 auto', padding:'60px 20px',
+        textAlign:'center'
+      }}>
+        <div style={{
+          background:'#FFF4E6',
+          border:'2px solid #F59E0B',
+          borderRadius:16, padding:'40px 24px', marginBottom:24
+        }}>
+          <div style={{fontSize:48, marginBottom:16}}>⏰</div>
+          <h2 style={{marginBottom:12, color:'#D97706'}}>
+            Verifikations-Link abgelaufen
+          </h2>
+          <p style={{color:'var(--text2)', lineHeight:1.6, marginBottom:24}}>
+            Dieser Link ist leider nicht mehr gültig. Bitte fordere eine neue Bestätigungs-E-Mail an.
+          </p>
+
+          {resendSuccess ? (
+            <div style={{
+              background:'var(--accent-light)',
+              border:'1px solid var(--accent)',
+              borderRadius:8, padding:'16px', marginBottom:16
+            }}>
+              <div style={{fontSize:32, marginBottom:8}}>✓</div>
+              <div style={{fontWeight:600, color:'var(--accent-dark)', marginBottom:4}}>
+                E-Mail versendet!
+              </div>
+              <p style={{fontSize:13, color:'var(--text2)', margin:0}}>
+                Bitte prüfe dein Postfach.
+              </p>
+            </div>
+          ) : (
+            <>
+              <input
+                type="email"
+                className="form-input"
+                placeholder="deine@email.de"
+                value={email}
+                onChange={e => setEmail(e.target.value)}
+                onKeyDown={e => e.key === 'Enter' && handleResend()}
+                style={{width:'100%', boxSizing:'border-box', marginBottom:12}}
+                autoFocus
+              />
+
+              {error && (
+                <div style={{
+                  background:'rgba(216,90,48,0.1)',
+                  color:'#D85A30',
+                  fontSize:13,
+                  padding:'10px 14px',
+                  borderRadius:8,
+                  marginBottom:12,
+                  border:'1px solid rgba(216,90,48,0.2)'
+                }}>
+                  {error}
+                </div>
+              )}
+
+              <button
+                onClick={handleResend}
+                disabled={resending || !email.trim()}
+                className="btn btn-primary btn-full"
+                style={{marginBottom:12}}
+              >
+                {resending ? (
+                  <><div className="spinner" style={{width:14,height:14}}/> Sende...</>
+                ) : (
+                  'Neue Bestätigungs-E-Mail senden'
+                )}
+              </button>
+            </>
+          )}
+        </div>
+
+        <button
+          onClick={() => navigate('/login')}
+          style={{
+            background:'none', border:'none', cursor:'pointer',
+            fontSize:13, color:'var(--text3)', textDecoration:'underline'
+          }}
+        >
+          Zurück zum Login
+        </button>
+      </div>
+    )
+  }
+
   if (status === 'error') {
     return (
       <div style={{
@@ -81,9 +200,21 @@ export default function Verify() {
         <button
           onClick={() => navigate('/register')}
           className="btn btn-primary btn-full"
+          style={{marginBottom:12}}
         >
           Zur Registrierung
         </button>
+
+        <button
+          onClick={() => navigate('/login')}
+          style={{
+            background:'none', border:'none', cursor:'pointer',
+            fontSize:13, color:'var(--text3)', textDecoration:'underline',
+            width:'100%'
+          }}
+        >
+          Zum Login
+        </button>
       </div>
     )
   }

frontend/src/utils/api.js

@@ -144,6 +144,7 @@ export const api = {
   changePin:            (pin)     => req('/auth/pin',json({pin})),
   register:             (name,email,password) => req('/auth/register',json({name,email,password})),
   verifyEmail:          (token)   => req(`/auth/verify/${token}`),
+  resendVerification:   (email)   => req('/auth/resend-verification',json({email})),
 
   // v9c Subscription System
   // User-facing