feat(order): 添加订单流程标识返回字段

- 在预下单成功响应中增加 flow 字段
- 返回支付宝订单流程标识 flowFlag 信息
- 保持原有邮费价格字段不变

app/controller/api/store/order/AlibabaOrder.php

@@ -54,6 +54,6 @@ class AlibabaOrder
         if (!$res) {
             return app('json')->fail('预下单失败');
         }
-        return app('json')->success(['postagePrice' => $res['preview']['sumCarriage'] / 100]);
+        return app('json')->success(['postagePrice' => $res['preview']['sumCarriage'] / 100, 'flow' => $res['preview']['flowFlag']]);
     }
 }