发货链接返回完整域名：DELIVERY_BASE_URL 未配置时按请求 scheme+Host 推导

- GetOrCreateDeliveryLink/RestoreDeliveryLink 增加 requestBaseURL 参数
- buildDeliveryURL 优先级：DELIVERY_BASE_URL → 请求域名 → 路径
- 支持 X-Forwarded-Proto 与 TLS 判断 https

backend/internal/service/delivery_test.go

@@ -29,7 +29,7 @@ func TestDeliveryLinkGenerateAuthorizeAndRevoke(t *testing.T) {
 		t.Fatalf("create order: %v", err)
 	}
 
-	link, err := deliverySvc.GetOrCreateDeliveryLink(merchantID, created.Order.OrderNo)
+	link, err := deliverySvc.GetOrCreateDeliveryLink(merchantID, created.Order.OrderNo, "https://shop.example")
 	if err != nil {
 		t.Fatalf("get delivery link: %v", err)
 	}
@@ -61,7 +61,7 @@ func TestDeliveryLinkGenerateAuthorizeAndRevoke(t *testing.T) {
 		t.Fatalf("delivery_link_revoked_at should be stored")
 	}
 
-	restored, err := deliverySvc.RestoreDeliveryLink(merchantID, created.Order.OrderNo)
+	restored, err := deliverySvc.RestoreDeliveryLink(merchantID, created.Order.OrderNo, "https://shop.example")
 	if err != nil {
 		t.Fatalf("restore delivery link: %v", err)
 	}