UI-Anpassungen

frontend/js/app.js

@@ -733,7 +733,7 @@ class App {
     users.forEach(user => {
       const option = document.createElement('option');
       option.value = user.id;
-      option.textContent = user.username;
+      option.textContent = user.displayName || user.email || 'Unbekannt';
       select.appendChild(option);
     });
   }