feat(buyer): 更新电子卡券（E_COUPON）相关逻辑与展示

- 优化购物车与支付页面，确保电子卡券只能通过立即购买结算
- 增强商品详情页，添加限时折扣与第N件优惠展示
- 更新促销逻辑，支持拼团与积分购买选项
- 规范化商品类型与库存提示，提升用户体验

seller/src/constants/cardKey.js

@@ -11,18 +11,21 @@
 export const CARD_KEY_STATUS = {
   UNUSED: "UNUSED",
   ALLOCATED: "ALLOCATED",
+  RESERVED: "RESERVED",
   VOIDED: "VOIDED",
 };
 
 export const CARD_KEY_STATUS_TEXT = {
   UNUSED: "未使用",
   ALLOCATED: "已分配",
+  RESERVED: "已预占",
   VOIDED: "已作废",
 };
 
 export const CARD_KEY_STATUS_TAG = {
   UNUSED: "success",
   ALLOCATED: "info",
+  RESERVED: "warning",
   VOIDED: "danger",
 };
 
@@ -30,6 +33,7 @@ export const CARD_KEY_STATUS_TAG = {
 export const CARD_KEY_STATUS_TABS = [
   { key: "", label: "全部" },
   { key: CARD_KEY_STATUS.UNUSED, label: "未使用" },
+  { key: CARD_KEY_STATUS.RESERVED, label: "已预占" },
   { key: CARD_KEY_STATUS.ALLOCATED, label: "已分配" },
   { key: CARD_KEY_STATUS.VOIDED, label: "已作废" },
 ];