修复订单金额落库不对的问题

internal/model/order.go

@@ -152,7 +152,8 @@ type OrderItem struct {
 	PackageName              string  `gorm:"column:package_name;type:varchar(100);not null;comment:套餐名称(快照)" json:"package_name"`
 	PackageType              *string `gorm:"column:package_type;type:varchar(20);comment:套餐类型快照 formal-正式套餐 addon-加油包" json:"package_type"`
 	Quantity                 int     `gorm:"column:quantity;type:int;default:1;not null;comment:数量" json:"quantity"`
-	UnitPrice                int64   `gorm:"column:unit_price;type:bigint;not null;comment:单价(分)" json:"unit_price"`
+	UnitPrice                int64   `gorm:"column:unit_price;type:bigint;not null;comment:零售单价快照（分，客户面值）" json:"unit_price"`
+	CostPrice                int64   `gorm:"column:cost_price;type:bigint;not null;default:0;comment:成本单价快照（分，代购/钱包支付场景为买家成本，平台自营或赠送时为0）" json:"cost_price"`
 	Amount                   int64   `gorm:"column:amount;type:bigint;not null;comment:小计金额(分)" json:"amount"`
 	PackagePriceConfigStatus int     `gorm:"column:package_price_config_status;type:int;default:0;not null;comment:套餐价格配置状态快照 0-未配置 1-赠送0价 2-已配置非0" json:"package_price_config_status"`
 	PackageIsGift            bool    `gorm:"column:package_is_gift;type:boolean;default:false;not null;comment:套餐是否赠送快照 true-赠送 false-普通可售" json:"package_is_gift"`