implemented dual Nextcloud push registration with separate general and talk apptypes to ensure reliable Talk notification delivery; introduced stacked MessagingStyle notifications for chat threads with support for circular conversation avatars and disk caching

lib/main.dart

@@ -96,7 +96,7 @@ Future<void> main() async {
   // decrypts and renders Nextcloud pushes while the app is not in foreground.
   await NotificationService().initializeNotifications();
   await PushRenderer.ensureChannels();
-  FirebaseMessaging.onBackgroundMessage(PushMessageHandler.onBackgroundMessage);
+  FirebaseMessaging.onBackgroundMessage(pushOnBackgroundMessage);
 
   // Wire up the home-screen widget bridge before runApp so any widget render
   // triggered during startup hits initialised native storage.
@@ -375,13 +375,13 @@ class _MainState extends State<Main> {
                       return Stack(
                         fit: StackFit.expand,
                         children: [
-                          if (_appMounted) const App(key: ValueKey('app-shell')),
+                          if (_appMounted)
+                            const App(key: ValueKey('app-shell')),
                           if (_showPostLoginSplash)
                             PostLoginSplash(
                               key: const ValueKey('post-login-splash'),
-                              onComplete: () => setState(
-                                () => _showPostLoginSplash = false,
-                              ),
+                              onComplete: () =>
+                                  setState(() => _showPostLoginSplash = false),
                             ),
                         ],
                       );