优化：商品及订单优惠价格；支付说明；

api/modules/order.ts

@@ -8,7 +8,8 @@ import type {
   IOrderGoods,
   ICoupon,
   ICourseOrderCreateParams,
-  IOrderInitData
+  IOrderInitData,
+  IGoodsDiscountParams
 } from '@/types/order'
 import type { IUserInfo } from '@/types/user'
 
@@ -108,7 +109,7 @@ export const orderApi = {
    * 获取地区优惠金额
    * @param productList 商品列表
    */
-  async getDistrictAmount(productList: Array<{ productId: number; quantity: number }>) {
+  async getDistrictAmount(productList: IGoodsDiscountParams[]) {
     const res = await mainClient.request<IApiResponse<{ districtAmount: number }>>({
       url: 'book/buyOrder/getDistrictAmount',
       method: 'POST',