修复(#85): 促销系统 quantity 设计修正补丁（跨任务统一修复）

- subscribe_promo 表加 quantity 字段，BIGINT NOT NULL DEFAULT 1
- EvaluatePromo 加 quantity 参数，按 subscribeID + quantity 精确匹配
- Promo 从 Subscribe 顶层移到 SubscribeDiscount
- 查询加 quantity，返回 map[subscribeID][quantity] 二级映射
- recordPromoUsage 错误向上传播，不再静默吞掉
- preCreate 和 purchase 的 allowPromo 判定统一为 orderType==1
- 迁移脚本增加幂等处理（guarded DROP/ADD/MODIFY）

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

queue/logic/order/activateOrderLogic.go

@@ -149,7 +149,20 @@ func (l *ActivateOrderLogic) ProcessTask(ctx context.Context, task *asynq.Task)
 		return err
 	}
 
-	l.recordPromoUsage(ctx, orderInfo)
+	if err = l.recordPromoUsage(ctx, orderInfo); err != nil {
+		if releaseErr := l.releaseClaim(ctx, orderInfo.OrderNo); releaseErr != nil {
+			logger.WithContext(ctx).Error("[ActivateOrderLogic] releaseClaim also failed, stuck recovery will handle",
+				logger.Field("order_no", orderInfo.OrderNo),
+				logger.Field("release_error", releaseErr.Error()),
+			)
+		}
+		logger.WithContext(ctx).Error("[ActivateOrderLogic] 促销使用记录写入失败，将重试",
+			logger.Field("order_no", orderInfo.OrderNo),
+			logger.Field("promo_rule_id", orderInfo.PromoRuleId),
+			logger.Field("error", err.Error()),
+		)
+		return err
+	}
 	l.finalizeCouponAndOrder(ctx, orderInfo)
 
 	commonLogic.SubscriptionTraceInfo(logger.WithContext(ctx), commonLogic.SubscriptionTraceFlowOrder, "activation_finished",
@@ -159,9 +172,9 @@ func (l *ActivateOrderLogic) ProcessTask(ctx context.Context, task *asynq.Task)
 	return nil
 }
 
-func (l *ActivateOrderLogic) recordPromoUsage(ctx context.Context, orderInfo *order.Order) {
+func (l *ActivateOrderLogic) recordPromoUsage(ctx context.Context, orderInfo *order.Order) error {
 	if orderInfo == nil || orderInfo.PromoRuleId <= 0 || orderInfo.Quantity <= 0 || orderInfo.SubscribeId <= 0 || orderInfo.OrderNo == "" {
-		return
+		return nil
 	}
 
 	promoPrice := int64(0)
@@ -169,10 +182,10 @@ func (l *ActivateOrderLogic) recordPromoUsage(ctx context.Context, orderInfo *or
 		promoPrice = (orderInfo.Price - orderInfo.PromoDiscount) / orderInfo.Quantity
 	}
 	if promoPrice <= 0 {
-		return
+		return nil
 	}
 
-	err := l.svc.DB.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+	return 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
@@ -188,13 +201,6 @@ func (l *ActivateOrderLogic) recordPromoUsage(ctx context.Context, orderInfo *or
 			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