hotfix: ProtectedRoute allows access for system_admin + empty permissions + /kein-zugriff route + NoAccessPage

frontend/src/routes/index.tsx

@@ -64,6 +64,7 @@ const ActivityTimelinePage = React.lazy(() => import('@/pages/ActivityTimeline')
 const SettingsWebhooksPage = React.lazy(() => import('@/pages/SettingsWebhooks').then(m => ({ default: m.SettingsWebhooksPage })));
 const SettingsBackupPage = React.lazy(() => import('@/pages/SettingsBackup').then(m => ({ default: m.SettingsBackupPage })));
 const SettingsRechtePage = React.lazy(() => import('@/pages/SettingsRechte').then(m => ({ default: m.SettingsRechtePage })));
+const NoAccessPage = React.lazy(() => import('@/pages/NoAccessPage').then(m => ({ default: m.NoAccessPage })));
 
 /** Centered spinner fallback for lazy-loaded routes */
 function PageLoader() {
@@ -120,6 +121,10 @@ const router = createBrowserRouter([
     path: '/guest/contacts',
     element: <GuestContactsPage />,
   },
+  {
+    path: '/kein-zugriff',
+    element: <ErrorBoundary>{withSuspense(<NoAccessPage />)}</ErrorBoundary>,
+  },
   {
     element: (
       <ProtectedRoute>