修复(#79): 促销管理后台API + 审查问题修复

- 实现促销管理接口：规则CRUD、优惠价配置、使用记录查询
- 修复 UpsertPrices 新增记录时提前 return 的问题
- DeleteRule/DeletePrice 不存在记录返回 code=404
- SetPromoPriceRequest.items 空数组校验
- 分页参数限制 page>0、1<=size<=200
- 下单侧促销价格按数量档总价口径计算（含 #87 修复）

Co-authored-by: multica-agent <github@multica.ai>

internal/handler/routes.go

@@ -17,6 +17,7 @@ import (
 	adminMarketing "github.com/perfect-panel/server/internal/handler/admin/marketing"
 	adminOrder "github.com/perfect-panel/server/internal/handler/admin/order"
 	adminPayment "github.com/perfect-panel/server/internal/handler/admin/payment"
+	adminPromo "github.com/perfect-panel/server/internal/handler/admin/promo"
 	adminRedemption "github.com/perfect-panel/server/internal/handler/admin/redemption"
 	adminServer "github.com/perfect-panel/server/internal/handler/admin/server"
 	adminSubscribe "github.com/perfect-panel/server/internal/handler/admin/subscribe"
@@ -374,6 +375,38 @@ func RegisterHandlers(router *gin.Engine, serverCtx *svc.ServiceContext) {
 		adminPaymentGroupRouter.GET("/platform", adminPayment.GetPaymentPlatformHandler(serverCtx))
 	}
 
+	adminPromoGroupRouter := router.Group("/v1/admin/promo")
+	adminPromoGroupRouter.Use(middleware.AuthMiddleware(serverCtx))
+
+	{
+		// Create promo rule
+		adminPromoGroupRouter.POST("/rule", adminPromo.CreateRuleHandler(serverCtx))
+
+		// Get promo rule list
+		adminPromoGroupRouter.GET("/rule/list", adminPromo.GetRuleListHandler(serverCtx))
+
+		// Get promo rule detail
+		adminPromoGroupRouter.GET("/rule/:id", adminPromo.GetRuleDetailHandler(serverCtx))
+
+		// Update promo rule
+		adminPromoGroupRouter.PUT("/rule/:id", adminPromo.UpdateRuleHandler(serverCtx))
+
+		// Delete promo rule
+		adminPromoGroupRouter.DELETE("/rule/:id", adminPromo.DeleteRuleHandler(serverCtx))
+
+		// Set promo prices
+		adminPromoGroupRouter.POST("/price", adminPromo.SetPriceHandler(serverCtx))
+
+		// Get promo price list
+		adminPromoGroupRouter.GET("/price/list", adminPromo.GetPriceListHandler(serverCtx))
+
+		// Delete promo price
+		adminPromoGroupRouter.DELETE("/price/:id", adminPromo.DeletePriceHandler(serverCtx))
+
+		// Get promo usage list
+		adminPromoGroupRouter.GET("/usage/list", adminPromo.GetUsageListHandler(serverCtx))
+	}
+
 	adminRedemptionGroupRouter := router.Group("/v1/admin/redemption")
 	adminRedemptionGroupRouter.Use(middleware.AuthMiddleware(serverCtx))