feat(video_calls): fixed online indicator and in app notifications for video call

lib/features/chat/models/chat_user_model.dart

@@ -10,6 +10,8 @@ abstract class ChatUserModel with _$ChatUserModel {
     required String name,
     required String slug,
     @JsonKey(name: 'profile_photo_url') String? profilePhotoUrl,
+    @Default(false) @JsonKey(name: 'is_online') bool isOnline,
+    @Default('') @JsonKey(name: 'last_seen_text') String lastSeenText,
   }) = _ChatUserModel;
 
   factory ChatUserModel.fromJson(Map<String, Object?> json) => _$ChatUserModelFromJson(json);