fix(distribution): 修复收号站订单详情权限、专属支付通道路由、大盘统计与仲裁积分隔离

- 修复 FindOrder 在收号站模式(two_party_distributor_receive / three_party)下的 403 权限判定，放行参与方站点成员并精准计算收益
- 串联 distribution_site_payment_channels 至 payment.Start 核心支付发起流程，分销订单优先使用绑定的专属商户通道
- 修复数据大盘 GetDashboardAnalytics 趋势中 ReceivedCount 恒为 0 的问题，并对齐今日订单与 GMV 统计
- 修复 dispute/arbitration.go 仲裁完成时向分销租客发放成长积分的泄漏风险
- 提现管理新增 distribution_site_name/distribution_site_code 字段并在后台列表与详情弹窗中区分展示分销站
- GetPublicSiteInfo 增加 X-Distribution-Site-Code 请求头兜底支持

backend/internal/modules/withdrawal/repository_integration_test.go

@@ -168,3 +168,33 @@ func TestWithdrawalCreateRollsBackWhenBalanceIsInsufficient(t *testing.T) {
 	}
 	f.assertBalance(t, 100_000, 0)
 }
+
+func TestWithdrawalDetailIncludesDistributionSiteInfo(t *testing.T) {
+	f := newWithdrawalFixture(t)
+	if err := f.db.AutoMigrate(&model.DistributionSite{}); err != nil {
+		t.Fatal(err)
+	}
+	site := model.DistributionSite{SiteCode: "sub_site", SiteName: "分销子站", Domain: "sub.example.com", Status: "active"}
+	if err := f.db.Create(&site).Error; err != nil {
+		t.Fatal(err)
+	}
+	wReq := model.WithdrawalRequest{
+		WithdrawNo:         "WD2026TESTSITE",
+		UserID:             f.userID,
+		DistributionSiteID: site.ID,
+		AmountCent:         5000,
+		ActualAmountCent:   5000,
+		Status:             "pending",
+	}
+	if err := f.db.Create(&wReq).Error; err != nil {
+		t.Fatal(err)
+	}
+
+	detail, err := f.repo.AdminFindByID(context.Background(), wReq.ID)
+	if err != nil {
+		t.Fatalf("AdminFindByID failed: %v", err)
+	}
+	if detail.DistributionSiteID != site.ID || detail.DistributionSiteName != "分销子站" || detail.DistributionSiteCode != "sub_site" {
+		t.Fatalf("unexpected detail site info: %+v", detail)
+	}
+}