feat(订单服务): 添加订阅相关字段到订单查询

在订单查询结果中添加 isSubscription 标志和 related 订阅信息字段，以便前端展示订单的订阅状态和关联订阅详情

src/service/order.service.ts

@@ -643,6 +643,37 @@ export class OrderService {
         o.payment_method as payment_method,
         cs.order_count as order_count,
         cs.total_spent as total_spent,
+        CASE WHEN EXISTS (
+          SELECT 1 FROM subscription s
+          WHERE s.siteId = o.siteId AND s.parent_id = o.externalOrderId
+        ) THEN 1 ELSE 0 END AS isSubscription,
+        (
+          SELECT COALESCE(
+            JSON_ARRAYAGG(
+              JSON_OBJECT(
+                'id', s.id,
+                'externalSubscriptionId', s.externalSubscriptionId,
+                'status', s.status,
+                'currency', s.currency,
+                'total', s.total,
+                'billing_period', s.billing_period,
+                'billing_interval', s.billing_interval,
+                'customer_id', s.customer_id,
+                'customer_email', s.customer_email,
+                'parent_id', s.parent_id,
+                'start_date', s.start_date,
+                'trial_end', s.trial_end,
+                'next_payment_date', s.next_payment_date,
+                'end_date', s.end_date,
+                'line_items', s.line_items,
+                'meta_data', s.meta_data
+              )
+            ),
+            JSON_ARRAY()
+          )
+          FROM subscription s
+          WHERE s.siteId = o.siteId AND s.parent_id = o.externalOrderId
+        ) AS related,
         COALESCE(
           JSON_ARRAYAGG(
             CASE WHEN s.id IS NOT NULL THEN JSON_OBJECT(