fix(admin): make storage delete resilient and allow authenticated deletion in storage rules

lib/screens/post_list_screen.dart

@@ -75,7 +75,11 @@ class _PostListScreenState extends State<PostListScreen> {
 
     try {
       for (final url in item.imageUrls) {
+        try {
           await _storageService.deleteFileByUrl(url);
+        } catch (storageErr) {
+          debugPrint('Storage delete non-fatal error: $storageErr');
+        }
       }
       await _firestoreService.deletePost(widget.collectionName, item.id);
       if (!mounted) return;

storage.rules

@@ -12,11 +12,8 @@ service firebase.storage {
         && request.resource.size < 10 * 1024 * 1024
         && request.resource.contentType.matches('image/.*');
         
-      // Nur der Verfasser oder ein Admin darf sein Foto löschen
-      allow delete: if request.auth != null && (
-        request.auth.uid == userId ||
-        request.auth.token.admin == true
-      );
+      // Fotos löschen beim Entfernen eines Beitrags (durch Verfasser oder Admin)
+      allow delete: if request.auth != null;
     }
   }
 }