fix: 修复业务员端订单表单快递公司提示和rebate_total字段映射

frontend/web-sales/src/views/OrderFormPage.vue

@@ -335,7 +335,7 @@
             <input v-model.trim="form.tracking_number" type="text" placeholder="" />
           </label>
           <label v-if="!form.is_self_pickup">
-            <span>快递公司（可选）</span>
+            <span>快递公司（必选）</span>
             <ExpressCompanyField v-model="form.express_company" />
           </label>
         </div>
@@ -960,7 +960,7 @@ async function handleSubmit() {
       customer_demand: form.customer_demand,
       contract_amount: form.contract_amount,
       freight_total: form.freight_total,
-      rebate_total: form.rebate_total,
+      rebate_total: form.commission_amount,
       tax_total: form.tax_total,
       other_fee_total: form.other_fee_total,
       commission_amount: form.commission_amount,