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/components/ui/StepBar.vue

@@ -0,0 +1,50 @@
+<script setup lang="ts">
+defineProps<{ steps: string[]; active: number }>();
+</script>
+
+<template>
+  <ol class="steps">
+    <li v-for="(s, i) in steps" :key="s" :class="{ done: i < active, on: i === active }">
+      <span class="n">{{ i + 1 }}</span>
+      <span class="label">{{ s }}</span>
+    </li>
+  </ol>
+</template>
+
+<style scoped>
+.steps {
+  display: flex;
+  list-style: none;
+  margin: 0 0 20px;
+  padding: 14px 0;
+  background: #fafafa;
+  border: 1px solid var(--mall-line);
+}
+li {
+  flex: 1;
+  text-align: center;
+  color: var(--mall-faint);
+  font-size: 13px;
+}
+.n {
+  display: inline-block;
+  width: 22px;
+  height: 22px;
+  line-height: 22px;
+  border-radius: 50%;
+  background: #ddd;
+  color: #fff;
+  margin-right: 8px;
+  font-size: 12px;
+}
+li.on {
+  color: var(--mall-red);
+  font-weight: 600;
+}
+li.on .n {
+  background: var(--mall-red);
+}
+li.done .n {
+  background: var(--mall-green);
+}
+</style>