refactor(create-order): 优化回款概览信息展示逻辑

- 移除了对 isBackstageOrder 的判断，统一展示格式
- 使用 || 运算符优化了空值展示逻辑，提高代码可读性

Signed-off-by: tangshizhe <48740614+tangshizhe@users.noreply.github.com>

src/views/create-order/components/order-detail-submodule/PaymentInfo.vue

@@ -3,13 +3,13 @@
     <InfoCard title="回款概览">
       <div class="payment-info-content">
         <div class="payment-info-item">
-          回款状态：{{ isBackstageOrder ? returnStatus : '-' }}
+          回款状态：{{ returnStatus || '-' }}
         </div>
         <div class="payment-info-item">
-          已回款金额：{{isBackstageOrder ? '¥' + returnAmount(returnRes?.returnMoney) : '-'}}
+          已回款金额：{{'¥' + returnAmount(returnRes?.returnMoney) || '-'}}
         </div>
         <div class="payment-info-item">
-          未回款金额：{{ isBackstageOrder? '¥' + returnAmount(returnRes?.remainingMoney) : '-' }}
+          未回款金额：{{ '¥' + returnAmount(returnRes?.remainingMoney) || '-' }}
         </div>
       </div>
     </InfoCard>