fix: 一尘看板按最新帖子发表时间排序 - 使用COALESCE(post_time, crawled_at)

backend/app/routers/yichens.py

@@ -138,13 +138,13 @@ def get_posts(
     count_query = f"SELECT COUNT(*) FROM yichens_posts WHERE {where_sql}"
     total_count = db.execute(text(count_query), {k: v for k, v in params.items() if k not in ['limit', 'offset']}).scalar() or 0
     
-    # 查询数据
+    # 查询数据 - 有post_time时按post_time排序，没有时按crawled_at排序
     data_query = f"""
         SELECT post_id, title, content, category, post_type, price, 
                author_username, post_time, reply_count, view_count, url
         FROM yichens_posts
         WHERE {where_sql}
-        ORDER BY post_time DESC LIMIT :limit OFFSET :offset
+        ORDER BY COALESCE(post_time, crawled_at) DESC LIMIT :limit OFFSET :offset
     """
     results = db.execute(text(data_query), params).fetchall()