feat(ui): adopt Tailwind v4 design system and archive change

- Add tailwindcss v4 + @tailwindcss/vite to mall, shop-admin, admin
- Add @vmall/shared/theme.css tokens with html[data-accent] presets
- Add @vmall/ui kit (VBtn/VBadge/VField/VInput/VCard/VPanel/VTable/VPage,
  VAccentSwatch, useAccent) as a Nuxt module
- Convert all three apps to kit + utilities; delete ui.css/mall.css and
  every <style scoped>; consoles get accent presets, mall locked to red
- Fix VCard boolean prop default (padding) and PDP/store stale
  useAsyncData keys on param navigation
- Archive adopt-tailwind-design-system; new frontend-ui capability spec

apps/mall/pages/user/coupons.vue

@@ -32,12 +32,12 @@ onMounted(() => void load());
 </script>
 
 <template>
-  <section class="mpanel coupons-panel">
-    <h1 class="mpanel-title">{{ t("user.couponsTitle") }}</h1>
-    <p v-if="error" class="error-message">{{ error }}</p>
-    <div v-else-if="loading" class="loading-state">{{ t("common.loading") }}</div>
+  <VCard class="min-h-[560px]">
+    <h1 class="mb-4 text-xl font-bold text-text">{{ t("user.couponsTitle") }}</h1>
+    <p v-if="error" class="mb-4 border border-danger/30 bg-danger/10 px-3.5 py-2.5 text-danger">{{ error }}</p>
+    <div v-else-if="loading" class="py-10 text-muted">{{ t("common.loading") }}</div>
     <UiEmptyState v-else-if="coupons.length === 0" :text="t('user.noCoupons')" />
-    <table v-else class="mtable">
+    <VTable v-else>
       <thead>
         <tr>
           <th>{{ t("user.couponTitle") }}</th>
@@ -56,23 +56,7 @@ onMounted(() => void load());
           <td>{{ statusLabels[coupon.status] ?? coupon.status }}</td>
         </tr>
       </tbody>
-    </table>
-  </section>
+    </VTable>
+  </VCard>
 </template>
 
-<style scoped>
-.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>