security: M-2 HttpOnly-Cookie + M-4 TrustedHost-Warning + M-5 TOTP-Lockout + M-7 zentraler get_client_ip()

M-2: Refresh-Token als HttpOnly SameSite=Strict Cookie
- auth.py: _set_refresh_cookie/_delete_refresh_cookie Helpers
- Alle Auth-Endpoints (login, totp/login, refresh, logout) nutzen Cookie
- schemas/auth.py: refresh_token in Request/Response optional
- AuthContext.tsx: kein refresh_token in localStorage
- api/client.ts: credentials:include, kein Token-Body beim Refresh

M-4: TrustedHostMiddleware Warning in Production
- main.py: Startup-Warning wenn is_production + kein ALLOWED_HOSTS

M-5: TOTP-Fehlversuche Redis-Lockout
- auth.py: _check/_record/_clear_totp_lockout; 5 Versuche → 15 min Sperre

M-7: Zentraler get_client_ip()-Helper
- core/dependencies.py: get_client_ip() mit X-Real-IP → X-Forwarded-For → client.host
- hours_payouts.py, absences.py, busylight.py: request.client.host ersetzt

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

frontend/src/context/AuthContext.tsx

@@ -17,19 +17,25 @@ export function AuthProvider({ children }: { children: ReactNode }) {
   const navigate = useNavigate()
 
   async function login(email: string, password: string) {
-    const data = await api.post<{ access_token: string; refresh_token: string }>(
+    // refresh_token kommt nicht mehr im Body – nur noch als HttpOnly-Cookie
+    const data = await api.post<{ access_token: string; refresh_token?: string | null }>(
       '/auth/login',
       { email, password },
     )
     localStorage.setItem('access_token', data.access_token)
-    localStorage.setItem('refresh_token', data.refresh_token)
+    // refresh_token NICHT mehr in localStorage speichern (M-2: HttpOnly-Cookie)
     setToken(data.access_token)
     navigate('/dashboard')
   }
 
-  function logout() {
+  async function logout() {
+    // Cookie wird vom Backend gelöscht; kein refresh_token aus localStorage nötig
+    try {
+      await api.post('/auth/logout', {})
+    } catch {
+      // Logout-Fehler ignorieren – lokal trotzdem ausloggen
+    }
     localStorage.removeItem('access_token')
-    localStorage.removeItem('refresh_token')
     setToken(null)
     navigate('/login')
   }