feat(playlist): 优化歌单详情页面加载逻辑

- 将评论获取移至歌单详情获取成功后
- 添加评论数到歌单 DTO
- 优化前端歌单详情展示

music-houduan/src/main/java/com/test/musichouduan/service/impl/PlaylistServiceImpl.java

@@ -75,6 +75,9 @@ public class PlaylistServiceImpl implements PlaylistService {
     @Autowired
     private PlayHistoryRepository playHistoryRepository;
 
+    @Autowired
+    private CommentRepository commentRepository;
+
     @Autowired
     private FileService fileService;
 
@@ -590,6 +593,10 @@ public class PlaylistServiceImpl implements PlaylistService {
             playlistDTO.setSongCount(0);
         }
 
+        // 设置评论数 (targetType=2 代表歌单)
+        long commentCount = commentRepository.countByTargetIdAndTargetType(playlist.getId(), 2);
+        playlistDTO.setCommentCount((int) commentCount);
+
         // 检查当前登录用户是否已收藏该歌单
         if (StpUtil.isLogin()) {
             Long userId = StpUtil.getLoginIdAsLong();