feat: manueller Backup-Button für Admin

POST /api/backup (nur Admin) löst triggerBackup() aus.
Button im Header zeigt ⏳/✓/✗ Feedback, verschwindet nach 4s.

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

app/MainClient.tsx

@@ -21,6 +21,7 @@ export default function MainClient({ kuerzel, beoId, beoName, role }: Props) {
   const [activeTab, setActiveTab] = useState<'eingabe' | 'liste' | 'statistik' | 'fahrkosten'>('eingabe');
   const [refreshKey, setRefreshKey] = useState(0);
   const [editEntry, setEditEntry] = useState<LogbuchEintrag | null>(null);
+  const [backupState, setBackupState] = useState<'idle' | 'running' | 'ok' | 'error'>('idle');
 
   const grafikSrc = '/api/statistik/grafik';
 
@@ -47,6 +48,17 @@ export default function MainClient({ kuerzel, beoId, beoName, role }: Props) {
     window.location.href = '/login';
   }
 
+  async function handleBackup() {
+    setBackupState('running');
+    try {
+      const r = await fetch('/api/backup', { method: 'POST' });
+      setBackupState(r.ok ? 'ok' : 'error');
+    } catch {
+      setBackupState('error');
+    }
+    setTimeout(() => setBackupState('idle'), 4000);
+  }
+
   return (
     <div className="min-h-screen bg-white py-1 px-2 sm:py-2 sm:px-4 print:p-0">
       <main className="max-w-6xl mx-auto border-2 border-black rounded-lg p-3 sm:p-4 bg-[#EEF4FF] print:max-w-none print:border-0 print:p-0 print:bg-white">
@@ -59,12 +71,25 @@ export default function MainClient({ kuerzel, beoId, beoName, role }: Props) {
           </h1>
           <div className="flex items-center gap-2 shrink-0">
             {role?.includes('admin') && (
-              <a
-                href="/admin"
-                className="text-xs sm:text-sm px-2 sm:px-3 py-1.5 bg-gray-200 hover:bg-gray-300 rounded-lg text-gray-700"
-              >
-                Admin
-              </a>
+              <>
+                <button
+                  onClick={handleBackup}
+                  disabled={backupState === 'running'}
+                  className={`text-xs sm:text-sm px-2 sm:px-3 py-1.5 rounded-lg text-gray-900 disabled:opacity-50 ${
+                    backupState === 'ok' ? 'bg-green-200' :
+                    backupState === 'error' ? 'bg-red-200' :
+                    'bg-gray-200 hover:bg-gray-300'
+                  }`}
+                >
+                  {backupState === 'running' ? '⏳ Backup…' : backupState === 'ok' ? '✓ Backup OK' : backupState === 'error' ? '✗ Fehler' : '💾 Backup'}
+                </button>
+                <a
+                  href="/admin"
+                  className="text-xs sm:text-sm px-2 sm:px-3 py-1.5 bg-gray-200 hover:bg-gray-300 rounded-lg text-gray-700"
+                >
+                  Admin
+                </a>
+              </>
             )}
             <button
               onClick={handleLogout}

app/api/backup/route.ts

@@ -0,0 +1,12 @@
+import { NextResponse } from 'next/server';
+import { getSession } from '@/lib/session';
+import { triggerBackup } from '@/lib/backup';
+
+export async function POST() {
+  const session = await getSession();
+  if (!session) return NextResponse.json({ error: 'Nicht angemeldet' }, { status: 401 });
+  if (!session.role?.includes('admin')) return NextResponse.json({ error: 'Keine Berechtigung' }, { status: 403 });
+
+  triggerBackup();
+  return NextResponse.json({ ok: true });
+}