Problem: Frontend JS bundle used credentials:'same-origin' which
dropped cookies on cross-domain requests. Login worked (200) but
the subsequent /auth/me check returned 401, leaving the user stuck
on the login screen.
Fix:
- AuthController now sets a dtp_jwt HttpOnly cookie on login/refresh
- Cookie uses Domain=.fahrschultermin.de (shared between frontend
and api subdomain), Secure, SameSite=Lax, Max-Age=8h
- JwtMiddleware reads JWT from Authorization header OR cookie
- Added AuthController::me() endpoint (was missing, caused 500)
- Logout endpoint clears the cookie
- Frontend index.php patches fetch() to use credentials:'include'
for all /api/v1/* calls
