实现价格折扣动态调整

src/models/product_sku.ts

@@ -1,12 +1,13 @@
 import type { Model } from "./base/model"
 import type { Product } from "./product"
+import type { ProductDiscount } from "./product_discount"
 
 export type ProductSku = Model & {
   product_id: number
   code: string
   name: string
   price: string
-  discount: number
 
   product?: Product
+  discount?: ProductDiscount
 }