fix: implement safe map casting for socket events and add support for conversation deletion updates

lib/features/messaging/presentation/providers/messaging_provider.dart

@@ -240,6 +240,27 @@ class MessagingNotifier extends StateNotifier<MessagingState> {
       state = state.copyWith(conversations: updatedConversations, messages: newMessages);
     }));
 
+    // Conversation deleted by other party — remove from local state
+    _subscriptions.add(_socket.onConversationDeleted.listen((data) {
+      if (!mounted) return;
+      final convId = data['conversationId'] as String?;
+      if (convId == null) return;
+
+      final updatedMessages =
+          Map<String, List<ChatMessage>>.from(state.messages)..remove(convId);
+      final updatedConversations =
+          state.conversations.where((c) => c.id != convId).toList();
+      final totalUnread = updatedConversations.fold<int>(
+        0, (sum, c) => sum + c.unreadCount,
+      );
+      state = state.copyWith(
+        messages: updatedMessages,
+        conversations: updatedConversations,
+        unreadCount: totalUnread,
+        clearActiveConversation: state.activeConversationId == convId,
+      );
+    }));
+
     // Reconnection: re-join active conversation room and catch up missed messages
     _subscriptions.add(_socket.onConnectionChange.listen((connected) {
       if (!mounted || !connected) return;