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

lib/api/demo/data/demo_capabilities.dart

@@ -0,0 +1,33 @@
+import '../../../state/app/modules/capabilities/bloc/capabilities_state.dart';
+import '../../../state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_state.dart';
+
+/// Demo fixtures for the mobile capability flags — everything granted so the
+/// demo persona sees every feature (incl. push) as available.
+class DemoCapabilities {
+  const DemoCapabilities._();
+
+  static CapabilitiesState state() => const CapabilitiesState(
+    viewForeignTimetables: true,
+    pushNotifications: true,
+    loaded: true,
+  );
+}
+
+/// Demo fixtures for the Nextcloud `files_sharing` capabilities — a permissive
+/// "everything enabled, nothing enforced" server profile.
+class DemoNextcloudCapabilities {
+  const DemoNextcloudCapabilities._();
+
+  static NextcloudCapabilitiesState state() => const NextcloudCapabilitiesState(
+    apiEnabled: true,
+    publicEnabled: true,
+    publicMultipleLinks: true,
+    publicUploadEnabled: true,
+    publicPasswordEnforced: false,
+    publicExpireEnabled: false,
+    publicExpireEnforced: false,
+    groupEnabled: true,
+    resharing: true,
+    loaded: true,
+  );
+}