新功能(#76): 促销系统下单流程集成

- 新增促销规则/规格促销价/使用记录模型与幂等迁移
- EvaluatePromo 支持 new_user/inactive_user/campaign 规则判定
- purchase/preCreate 接入促销判定：命中促销时跳过百分比折扣
- activate 激活后按 order_no 幂等写入 promo_usage
- 订单模型和响应结构新增 promo_rule_id、promo_discount 字段

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

queue/logic/order/activateOrderLogic.go

@@ -19,6 +19,7 @@ import (
 	"github.com/google/uuid"
 	"github.com/hibiken/asynq"
 	"github.com/perfect-panel/server/internal/model/order"
+	"github.com/perfect-panel/server/internal/model/promo"
 	"github.com/perfect-panel/server/internal/model/redemption"
 	"github.com/perfect-panel/server/internal/model/subscribe"
 	"github.com/perfect-panel/server/internal/model/user"
@@ -148,6 +149,7 @@ func (l *ActivateOrderLogic) ProcessTask(ctx context.Context, task *asynq.Task)
 		return err
 	}
 
+	l.recordPromoUsage(ctx, orderInfo)
 	l.finalizeCouponAndOrder(ctx, orderInfo)
 
 	commonLogic.SubscriptionTraceInfo(logger.WithContext(ctx), commonLogic.SubscriptionTraceFlowOrder, "activation_finished",
@@ -157,6 +159,44 @@ func (l *ActivateOrderLogic) ProcessTask(ctx context.Context, task *asynq.Task)
 	return nil
 }
 
+func (l *ActivateOrderLogic) recordPromoUsage(ctx context.Context, orderInfo *order.Order) {
+	if orderInfo == nil || orderInfo.PromoRuleId <= 0 || orderInfo.Quantity <= 0 || orderInfo.SubscribeId <= 0 || orderInfo.OrderNo == "" {
+		return
+	}
+
+	promoPrice := int64(0)
+	if orderInfo.Price > orderInfo.PromoDiscount {
+		promoPrice = (orderInfo.Price - orderInfo.PromoDiscount) / orderInfo.Quantity
+	}
+	if promoPrice <= 0 {
+		return
+	}
+
+	err := l.svc.DB.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+		var count int64
+		if e := tx.Model(&promo.Usage{}).Where("order_no = ?", orderInfo.OrderNo).Count(&count).Error; e != nil {
+			return e
+		}
+		if count > 0 {
+			return nil
+		}
+		return l.svc.PromoModel.InsertUsage(ctx, &promo.Usage{
+			UserId:      orderInfo.UserId,
+			PromoRuleId: orderInfo.PromoRuleId,
+			SubscribeId: orderInfo.SubscribeId,
+			OrderNo:     orderInfo.OrderNo,
+			PromoPrice:  promoPrice,
+		}, tx)
+	})
+	if err != nil {
+		logger.WithContext(ctx).Error("Insert promo usage failed",
+			logger.Field("error", err.Error()),
+			logger.Field("order_no", orderInfo.OrderNo),
+			logger.Field("promo_rule_id", orderInfo.PromoRuleId),
+		)
+	}
+}
+
 // parsePayload unMarshals the task payload into a structured format
 func (l *ActivateOrderLogic) parsePayload(ctx context.Context, payload []byte) (*queueTypes.ForthwithActivateOrderPayload, error) {
 	var p queueTypes.ForthwithActivateOrderPayload