feat: 折扣方案添加子表按钮（折扣产品明细）

使用subtables配置，点击按钮跳转到discount_detail子表，
通过discountid字段关联筛选。

json/discount_list.json

@@ -28,6 +28,13 @@
       "update_data_url": "{{entire_url('../api/discount_update.dspy')}}",
       "delete_data_url": "{{entire_url('../api/discount_delete.dspy')}}"
     },
-    "logined_userorgid": "resellerid"
+    "logined_userorgid": "resellerid",
+    "subtables": [
+      {
+        "field": "discountid",
+        "title": "折扣产品明细",
+        "subtable": "discount_detail"
+      }
+    ]
   }
 }