test: 测试库改为模板克隆并纳入完整租号 e2e

每个包不再重复 DROP+迁移，清空改用 DELETE 并重置自增，go test ./... 从约 6 分钟降到十几秒。租号全链路改走 NewTestDB，去掉依赖额外 DSN 才会跑的过渡测试。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/internal/e2e/distribution_flow_test.go

@@ -18,27 +18,7 @@ import (
 
 func openDistributionE2EDB(t *testing.T) *gorm.DB {
 	t.Helper()
-	db := database.NewTestDB()
-	sqlDB, err := db.DB()
-	if err != nil {
-		t.Fatal(err)
-	}
-	sqlDB.SetMaxOpenConns(1)
-
-	if err := database.MigrateRentalTransactionTestSchema(db); err != nil {
-		t.Fatalf("migrate rental transaction schema failed: %v", err)
-	}
-	if err := database.AutoMigrateIfMissing(db,
-		&model.Role{}, &model.Permission{}, &model.AdminUserRole{}, &model.RolePermission{},
-		&model.PaymentMerchantConfig{},
-		&model.DistributionSiteMember{}, &model.DistributionRuleVersion{}, &model.DistributionOrderFinancial{},
-		&model.DistributionOrderParty{}, &model.DistributionSitePaymentChannel{},
-		&model.DistributionSettlementBatch{}, &model.DistributionSettlementItem{},
-		&model.WithdrawalRequest{},
-	); err != nil {
-		t.Fatalf("auto migrate distribution schema failed: %v", err)
-	}
-	return db
+	return database.NewTestDB()
 }
 
 // TestE2EScenario1_MainSiteReceive_SubSiteMarkupSell_Settlement