blocked all nextcloud requests in demo mode to stop fake-credential logins tripping brute-force protection

lib/state/app/modules/chat/bloc/chat_bloc.dart

@@ -3,6 +3,7 @@ import 'dart:developer';
 
 import 'package:flutter/widgets.dart';
 
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumcloud/talk/chat/get_chat_history.dart';
 import '../../../../../api/marianumcloud/talk/chat/get_chat_response.dart';
 import '../../../../../api/marianumcloud/talk/chat/long_poll_chat.dart';
@@ -262,7 +263,7 @@ class ChatBloc
   }
 
   void _startLongPoll(String token) {
-    if (!_appResumed) return;
+    if (!_appResumed || DemoMode.active) return;
     // A load chain may finish after the user switched chats (A→B); without this
     // guard the stale chain hijacks the long-poll back to A and merges A's
     // messages into B's state while B never receives live updates.