feat(mall): claim and redeem shop coupons from the storefront

The product page loads a shop's claimable coupons through the shared client and
claims them in place; the buyer coupon list reads owned snapshots with their
claimed/redeemed/expired state. Checkout offers each shop order at most one
owned coupon and submits only the choice; the pay page and order detail render
the server-persisted discount and reduced total, never a client figure.

Coupon fixtures leave the pages; the fixed-data adapter still serves the coupon
domain as the rollback path. The demo seed creates two deterministic templates
and claims them for the demo customer.

apps/mall/pages/user/coupons.vue

@@ -1,16 +1,42 @@
 <script setup lang="ts">
 import { t as pick } from "@vmall/shared";
-import { MOCK_COUPONS } from "~/mock/data";
+import type { Coupon } from "@vmall/shared";
 
 definePageMeta({ middleware: "auth" });
 
 const { locale, t } = useI18n();
+const { $api } = useNuxtApp();
+const coupons = ref<Coupon[]>([]);
+const loading = ref(true);
+const error = ref("");
+
+const statusLabels = computed<Record<string, string>>(() => ({
+  claimed: t("user.couponClaimed"),
+  redeemed: t("user.couponRedeemed"),
+  expired: t("user.couponExpired"),
+}));
+
+async function load(): Promise<void> {
+  loading.value = true;
+  error.value = "";
+  try {
+    coupons.value = await $api.listMyCoupons();
+  } catch {
+    error.value = t("user.loadFailed");
+  } finally {
+    loading.value = false;
+  }
+}
+
+onMounted(() => void load());
 </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')" />
+    <p v-if="error" class="error-message">{{ error }}</p>
+    <div v-else-if="loading" class="loading-state">{{ t("common.loading") }}</div>
+    <UiEmptyState v-else-if="coupons.length === 0" :text="t('user.noCoupons')" />
     <table v-else class="mtable">
       <thead>
         <tr>
@@ -18,14 +44,16 @@ const { locale, t } = useI18n();
           <th>{{ t("user.amount") }}</th>
           <th>{{ t("user.threshold") }}</th>
           <th>{{ t("user.expiresAt") }}</th>
+          <th>{{ t("user.couponStatus") }}</th>
         </tr>
       </thead>
       <tbody>
-        <tr v-for="coupon in MOCK_COUPONS" :key="coupon.id">
+        <tr v-for="coupon in 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>
+          <td><PriceText :amount-minor="coupon.amount_minor" :currency="coupon.currency" /></td>
+          <td><PriceText :amount-minor="coupon.threshold_minor" :currency="coupon.currency" /></td>
+          <td>{{ coupon.ends_at.slice(0, 10) }}</td>
+          <td>{{ statusLabels[coupon.status] ?? coupon.status }}</td>
         </tr>
       </tbody>
     </table>
@@ -36,4 +64,15 @@ const { locale, t } = useI18n();
 .coupons-panel {
   min-height: 560px;
 }
+.error-message {
+  margin: 0 0 16px;
+  padding: 10px 14px;
+  color: #b42318;
+  background: #fff1f0;
+  border: 1px solid #ffd6d2;
+}
+.loading-state {
+  padding: 40px 0;
+  color: var(--mall-muted);
+}
 </style>