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

lib/main.dart

@@ -11,11 +11,13 @@ import 'package:flutter/scheduler.dart' show timeDilation;
 import 'package:flutter/services.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:http/http.dart' as http;
 import 'package:jiffy/jiffy.dart';
 import 'package:loader_overlay/loader_overlay.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:persistent_bottom_nav_bar_v2/persistent_bottom_nav_bar_v2.dart';
 
+import 'api/demo/demo_http_client.dart';
 import 'api/marianumcloud/webdav/queries/list_files/list_files_cache.dart';
 import 'api/marianumconnect/auth/session_validator.dart';
 import 'api/marianumconnect/marianumconnect_endpoint.dart';
@@ -117,7 +119,11 @@ void _installErrorHandlers() {
   };
 }
 
-Future<void> main() async {
+// Everything runs inside the zone so every package:http client created by the
+// app (Talk, avatars, image caches) goes through DemoHttpClient.
+Future<void> main() => http.runWithClient(_main, DemoHttpClient.new);
+
+Future<void> _main() async {
   log('MarianumMobile started');
   WidgetsFlutterBinding.ensureInitialized();
   SessionManager().markUiEngine();