optimized avatar and linkify performance, refined navigation to preserve popups, implemented read marker caching, and added file size limits for saving, minor timetable details changes

lib/notification/notification_controller.dart

@@ -26,9 +26,17 @@ class NotificationController {
     BuildContext context,
   ) async {
     final pushToken = _extractChatToken(message);
-    final activeToken = context.read<ChatBloc>().state.data?.currentToken ?? '';
+    final chatBloc = context.read<ChatBloc>();
+    // hasOpenChat (not currentToken) is the source of truth here:
+    // currentToken sticks around after leaveChat so that didPopNext can
+    // re-claim a stacked chat. Using it would suppress notifications for
+    // the last-opened chat even after the user has navigated away.
+    final activeToken = chatBloc.state.data?.currentToken ?? '';
     final chatIsOpen =
-        pushToken != null && pushToken.isNotEmpty && pushToken == activeToken;
+        chatBloc.hasOpenChat &&
+        pushToken != null &&
+        pushToken.isNotEmpty &&
+        pushToken == activeToken;
 
     NotificationTasks.updateBadgeCount(message);