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

frontend/src/components/common/ProtectedRoute.tsx

@@ -1,6 +1,7 @@
 import React from 'react';
 import { Navigate } from 'react-router-dom';
 import { usePermission } from '@/hooks/usePermission';
+import { useAuthStore } from '@/store/authStore';
 
 interface ProtectedRouteProps {
   permission: string;
@@ -9,6 +10,19 @@ interface ProtectedRouteProps {
 
 export function ProtectedRoute({ permission, children }: ProtectedRouteProps) {
   const { hasPermission } = usePermission();
+  const user = useAuthStore((state) => state.user);
+
+  // If user is system admin, always allow
+  if (user?.is_system_admin) {
+    return <>{children}</>;
+  }
+
+  // If permissions array is empty or not loaded yet, allow access
+  // (better to show page and let backend 403 handle it than block everything)
+  const perms = user?.permissions || [];
+  if (perms.length === 0) {
+    return <>{children}</>;
+  }
 
   if (!hasPermission(permission)) {
     return <Navigate to="/kein-zugriff" replace />;