fix(agent): 添加空消息时的等待指示器显示

当接收到空消息时显示等待指示器，提升用户体验

lib/modules/agent/views/message_bubble.dart

@@ -159,6 +159,10 @@ class MessageBubble extends GetView<AgentController> {
       );
     }
 
+    if (!isUser && message.isEmpty) {
+      return _buildTypingIndicator();
+    }
+
     // 如果是图片消息，显示图片
     if (hasImage && imagePath != null) {
       // 如果消息是默认的[图片]标记，只显示图片
@@ -220,21 +224,6 @@ class MessageBubble extends GetView<AgentController> {
 
     // 判断消息内容，显示特殊卡片
     if (!isUser && meta != null) {
-      // 判断消息类型，显示不同的卡片
-      // if (meta!.keys.contains('music_play')) {
-      //   final card_music =
-      //       meta!["music_play"]['card_music'] as Map<String, dynamic>?;
-      //   if (card_music != null) {
-      //     final musicId = card_music['id'];
-      //     final musicName = card_music['name'] as String? ?? '未知歌曲';
-      //     final musicUrl = card_music['url'] as String? ?? '';
-      //     final musicSinger = card_music['sgener'] as String? ?? '未知歌手';
-      //     final musicImage = card_music['image'] as String? ?? '';
-      //     final ts = card_music['ts'] as int? ?? 0;
-      //     //音乐卡片
-      //     return buildMusicItem(context, musicId, musicName, musicUrl,
-      //         musicSinger, musicImage, ts);
-      //   }
       if (meta!.keys.contains('music_searchandplay_songs')) {
         final music_search_songs =
             meta!['music_searchandplay_songs'] as Map<String, dynamic>;