feat(role): add 'verwaltung' role with gated access to settings and tools

shop/app/admin/einstellungen/page.tsx

@@ -5,6 +5,8 @@ import { useState, useEffect } from 'react';
 import { Switch } from '@/components/ui/switch';
 import { Button } from '@/components/ui/button';
 import { Download, Upload, Database, AlertTriangle, Loader2 } from 'lucide-react';
+import { createClient } from '@/lib/supabase/client';
+import { useRouter } from 'next/navigation';
 
 export default function AdminSettings() {
   const [demoActive, setDemoActive] = useState(true);
@@ -13,11 +15,32 @@ export default function AdminSettings() {
   const [statusMsg, setStatusMsg] = useState('');
   const [statusType, setStatusType] = useState<'success' | 'error' | 'info' | ''>('');
   const [selectedFile, setSelectedFile] = useState<File | null>(null);
+  const [loading, setLoading] = useState(true);
+  const router = useRouter();
 
   useEffect(() => {
-    const state = localStorage.getItem('demo_banner_disabled') !== 'true';
-    setDemoActive(state);
-  }, []);
+    async function checkAccess() {
+      const supabase = createClient();
+      const { data: { user } } = await supabase.auth.getUser();
+      if (!user) {
+        router.push('/auth/login');
+        return;
+      }
+      const { data: userData } = await supabase
+        .from('users')
+        .select('role')
+        .eq('id', user.id)
+        .single();
+      if (!userData || userData.role === 'verwaltung') {
+        router.push('/admin');
+      } else {
+        const state = localStorage.getItem('demo_banner_disabled') !== 'true';
+        setDemoActive(state);
+        setLoading(false);
+      }
+    }
+    checkAccess();
+  }, [router]);
 
   const toggleDemo = (checked: boolean) => {
     setDemoActive(checked);
@@ -85,6 +108,10 @@ export default function AdminSettings() {
     }
   };
 
+  if (loading) {
+    return <div className="p-8 text-white flex justify-center items-center"><Loader2 className="w-8 h-8 animate-spin text-primary" /></div>;
+  }
+
   return (
     <div className="p-6 max-w-4xl mx-auto text-slate-900 dark:text-white space-y-8">
       {/* Page Header */}