fix: 完善直播结束通知与 WebSocket 连接

frontend/lib/l10n/app_localizations_zh.dart

@@ -158,6 +158,12 @@ class AppLocalizationsZh extends AppLocalizations {
   @override
   String get sendMessage => '发送消息...';
 
+  @override
+  String get liveStreamEnded => '主播已退出，直播已结束。';
+
+  @override
+  String get liveStreamEndedShort => '直播已结束';
+
   @override
   String get liveChat => '实时聊天';
 
@@ -364,6 +370,12 @@ class AppLocalizationsZhHant extends AppLocalizationsZh {
   @override
   String get sendMessage => '發送訊息...';
 
+  @override
+  String get liveStreamEnded => '主播已退出，直播已結束。';
+
+  @override
+  String get liveStreamEndedShort => '直播已結束';
+
   @override
   String get liveChat => '即時聊天';