feat(orderConfirm): 优化订单确认页面功能和样式

- 添加优惠券选择功能
- 增加商品数量选择
- 完善订单信息展示
- 优化支付流程
- 添加错误状态和加载状态处理
- 新增 OrderConfirmSkeleton 组件用于加载骨架屏

src/components/OrderConfirmSkeleton.scss

@@ -0,0 +1,78 @@
+.order-confirm-skeleton {
+  padding: 0;
+  background: #f5f5f5;
+
+  .skeleton-section {
+    background: #fff;
+    margin-bottom: 8px;
+    padding: 16px;
+  }
+
+  .skeleton-address {
+    display: flex;
+    align-items: flex-start;
+    gap: 12px;
+
+    &-content {
+      flex: 1;
+      display: flex;
+      flex-direction: column;
+      gap: 8px;
+    }
+  }
+
+  .skeleton-goods {
+    display: flex;
+    align-items: flex-start;
+    gap: 12px;
+
+    &-content {
+      flex: 1;
+      display: flex;
+      flex-direction: column;
+      gap: 8px;
+    }
+
+    &-price {
+      display: flex;
+      align-items: center;
+      gap: 12px;
+    }
+  }
+
+  .skeleton-payment {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+  }
+
+  .skeleton-price-item {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    margin-bottom: 12px;
+
+    &:last-child {
+      margin-bottom: 0;
+    }
+  }
+
+  .skeleton-remark {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+  }
+
+  .skeleton-bottom {
+    position: fixed;
+    bottom: 0;
+    left: 0;
+    right: 0;
+    background: #fff;
+    padding: 16px;
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    box-shadow: 0 -2px 4px rgba(0, 0, 0, 0.1);
+  }
+}