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

openspec/specs/frontend-mall/spec.md

@@ -4,23 +4,72 @@
 TBD - created by archiving change frontend-apps. Update Purpose after archive.
 ## Requirements
 ### Requirement: Localized storefront
-The mall SHALL render UI strings and catalog content in en or zh from one switcher, defaulting to en.
+The mall SHALL render every UI string and all catalog/store/marketing mock content in en or zh from one switcher, defaulting to en. Switching locale SHALL update the desktop shell and current page without a full reload.
 
 #### Scenario: switch to Chinese
 - **WHEN** a shopper switches locale to zh
-- **THEN** navigation, buttons and product names render in Chinese without reload errors
+- **THEN** navigation, buttons, product/store names and mock marketing content render in Chinese without reload errors
 
 ### Requirement: Multi-currency display
-The mall SHALL offer a currency switcher (enabled currencies from the API) converting SKU prices for display; checkout uses the selected currency.
+The mall SHALL offer a currency switcher sourced from the selected API adapter and SHALL convert product, cart and order prices through integer minor units and each currency's exponent. Mock mode SHALL use deterministic fixed conversion rates; live mode SHALL use the API.
 
 #### Scenario: switch currency
 - **WHEN** a shopper switches from USD to JPY on a product priced $10.00
-- **THEN** the displayed price reflects the API conversion rate (integer minor units)
+- **THEN** the displayed price reflects the selected adapter's conversion rate with JPY exponent 0 and no floating-point money arithmetic
 
 ### Requirement: Shopping flow
-A shopper SHALL be able to browse, view detail, add to cart, checkout with a shipping address, pay (mock), track shipments, confirm delivery, and request an invoice — all against the live API.
+A shopper SHALL be able to browse, view detail, add to cart, checkout with a shipping address, pay (mock), track orders/shipments, confirm delivery, and request an invoice through the selected API adapter. The MVP SHALL default to the fixed-data mock adapter and SHALL not require the live API.
 
 #### Scenario: end-to-end purchase
-- **WHEN** a registered shopper completes checkout on a non-empty cart
-- **THEN** orders appear under Orders and the cart is empty
+- **WHEN** a shopper completes checkout on a non-empty mock cart
+- **THEN** the resulting order appears in the buyer center and the cart is empty
+
+### Requirement: B2B2C mall-style PC storefront shell
+The mall SHALL render a buyer-facing desktop shell modeled on a classic B2B2C PC mall: a 30px utility bar, logo/search/cart header, dark primary navigation with a hover category mega-menu, a 1200px content grid, and a value-proposition footer. The visual language SHALL use #ca151e for brand/price/active states, #f5f5f5 section backgrounds, gray hairline borders, compact controls, and product-card hover lift/shadow. The implementation SHALL use Nuxt-native semantic components and SHALL NOT depend on Element Plus.
+
+#### Scenario: shopper opens any mall page
+- **WHEN** a shopper navigates to a buyer-facing route
+- **THEN** the shared desktop shell wraps the route content and its nav/search/cart controls are usable
+
+### Requirement: Mock API adapter
+The mall SHALL default to a fixed-data mock adapter that implements the existing `@vmall/shared` API client surface. The adapter SHALL support auth, catalog, currency conversion, cart mutation, checkout, order/payment/shipment state, and invoices without a backend. A runtime configuration switch SHALL select the live API client later without changing page call sites.
+
+#### Scenario: mall runs without backend
+- **WHEN** the mall starts with mock mode enabled and the API service is unavailable
+- **THEN** browsing, cart, checkout, payment, orders and invoice pages return deterministic mock data and remain functional
+
+### Requirement: Mock PC home page
+The mall home page SHALL render a hero carousel, a six-item quick-link strip with promotion tiles, and bilingual product floors with a left advert and product-card grid.
+
+#### Scenario: shopper lands on home
+- **WHEN** `/` loads in mock mode
+- **THEN** the carousel, quick links, promotions and every non-empty product floor render fixed mock content
+
+### Requirement: Product discovery pages
+The mall SHALL provide `/search` with breadcrumb, category, brand and sort controls, a five-column desktop product grid, pagination and an empty state. It SHALL provide `/goods/[id]` with image gallery/zoom, bilingual name/subtitle, integer-minor-unit prices, attribute and SKU selection, stock-aware quantity, coupons/activity summary, store card, sales rail, and detail/comments/after-sale tabs.
+
+#### Scenario: filter and inspect a product
+- **WHEN** a shopper filters the search page and opens a product
+- **THEN** matching mock cards are shown and selecting an in-stock SKU updates the displayed price, stock and cart target
+
+### Requirement: Mock transaction flow
+The mall SHALL provide a store-grouped cart, address-selecting checkout preview, mock payment selection and payment-success result. Cart quantity/removal, selection totals, checkout and mock payment SHALL update the in-memory mock state for the current browser session.
+
+#### Scenario: complete mock purchase
+- **WHEN** a shopper adds an in-stock SKU, checks out with a mock address and confirms a mock payment
+- **THEN** the cart is cleared, the success page is shown and the new order appears in the user order list
+
+### Requirement: Auth and buyer center
+The mall SHALL provide B2B2C mall-style login, register and forgot-password panels backed by deterministic mock auth. `/user` SHALL render a two-column buyer center with dashboard, order list/detail, addresses, favorites, coupons and invoices.
+
+#### Scenario: sign in and inspect buyer data
+- **WHEN** a shopper submits the mock login form and opens `/user`
+- **THEN** the buyer-center shell and fixed account/order/address/favorite/coupon/invoice data render without backend access
+
+### Requirement: Store and marketing pages
+The mall SHALL provide a store directory, store home, timed seckill page, collective-buy list and points-mall home using fixed bilingual mock content. Marketing pages MAY be display-only except navigation to product detail.
+
+#### Scenario: navigate storefront discovery channels
+- **WHEN** a shopper opens stores, seckill, collective or integral routes
+- **THEN** each page renders the appropriate B2B2C mall-style banner/filter/session/card layout and product links resolve to mock product details