feat(mall): classic B2B2C PC storefront with fixed mock API layer

- Mock adapter implementing @vmall/shared ApiClient (localStorage-persisted
  cart/orders/invoices), runtime switch via mockApi flag (default on)
- Fixed bilingual mock catalog: 3-level categories, 24 products w/ SKUs,
  stores, brands, banners, floors, seckill/collective/integral, comments,
  coupons, addresses, seeded orders/shipments/invoices
- B2B2C mall shell: top bar, logo/search/cart header, dark nav + category
  mega-menu, value-prop footer, back-to-top; 1200px grid, #ca151e theme
- UI primitives replacing element-plus: carousel, pagination, breadcrumb,
  qty stepper, rating stars, modal, tabs, step bar, product card
- Pages: home floors, search (filters/sort/paging), goods detail (SKU
  picker, store rail, review tabs), cart -> checkout -> pay -> success,
  auth pages, user center (dashboard/orders/addresses/favorites/coupons/
  invoices), stores, seckill, collective, integral
- i18n split into per-domain locale modules (en+zh)
- OpenSpec change mall-pc-storefront-replica archived; all specs green

apps/mall/pages/user/coupons.vue

@@ -0,0 +1,39 @@
+<script setup lang="ts">
+import { t as pick } from "@vmall/shared";
+import { MOCK_COUPONS } from "~/mock/data";
+
+definePageMeta({ middleware: "auth" });
+
+const { locale, t } = useI18n();
+</script>
+
+<template>
+  <section class="mpanel coupons-panel">
+    <h1 class="mpanel-title">{{ t("user.couponsTitle") }}</h1>
+    <UiEmptyState v-if="MOCK_COUPONS.length === 0" :text="t('user.noCoupons')" />
+    <table v-else class="mtable">
+      <thead>
+        <tr>
+          <th>{{ t("user.couponTitle") }}</th>
+          <th>{{ t("user.amount") }}</th>
+          <th>{{ t("user.threshold") }}</th>
+          <th>{{ t("user.expiresAt") }}</th>
+        </tr>
+      </thead>
+      <tbody>
+        <tr v-for="coupon in MOCK_COUPONS" :key="coupon.id">
+          <td>{{ pick(coupon.title, locale) }}</td>
+          <td><PriceText :amount-minor="coupon.amountMinor" :currency="coupon.currency" /></td>
+          <td><PriceText :amount-minor="coupon.thresholdMinor" :currency="coupon.currency" /></td>
+          <td>{{ coupon.expiresAt }}</td>
+        </tr>
+      </tbody>
+    </table>
+  </section>
+</template>
+
+<style scoped>
+.coupons-panel {
+  min-height: 560px;
+}
+</style>