implemented a comprehensive client-side demo mode triggered by a "demo@" username prefix, serving curated fixture data for all app modules

lib/state/app/modules/capabilities/bloc/capabilities_cubit.dart

@@ -2,6 +2,8 @@ import 'dart:developer';
 
 import 'package:hydrated_bloc/hydrated_bloc.dart';
 
+import '../../../../../api/demo/data/demo_capabilities.dart';
+import '../../../../../api/demo/demo_mode.dart';
 import '../../../../../api/marianumconnect/queries/get_capabilities/get_capabilities.dart';
 import 'capabilities_state.dart';
 
@@ -20,6 +22,10 @@ class CapabilitiesCubit extends HydratedCubit<CapabilitiesState> {
   /// state is marked `loaded` — a failed fetch never silently grants a
   /// capability, and an offline launch keeps whatever was cached.
   Future<void> load() async {
+    if (DemoMode.active) {
+      emit(DemoCapabilities.state());
+      return;
+    }
     try {
       final response = await GetCapabilities().run();
       emit(