feat: 点单商品列表/详情多返回介绍与对外销量

hqsp 增加 jieshao，保持 xiaoliang=duiwai_xiaoliang；详情补充 jieshao/duiwai_xiaoliang 别名。仅多字段，不影响其它俱乐部逻辑。

Co-authored-by: Cursor <cursoragent@cursor.com>

products/views/product_query.py

@@ -218,9 +218,11 @@ class ShangpinXiangqingHuoquView(APIView):
                 "biaoti": shangpin.biaoqian,
                 "biaoqian": shangpin.biaoqian,
                 "jiage": shangpin.jiage,
+                "jieshao": shangpin.jieshao or '',
                 "xiangqing": shangpin.jieshao,
                 "xiadanxuzhi": shangpin.xiadan_xuzhi,
                 "guize": shangpin.guize_tupian,
+                "duiwai_xiaoliang": shangpin.duiwai_xiaoliang or 0,
                 "xiaoliang": shangpin.duiwai_xiaoliang,
                 "kucun": shangpin.kucun,
                 "leixing_id": shangpin.leixing_id,