chore(openspec): archive add-customer-accounts

Sync the customer-accounts capability and the frontend-mall stats requirement
into the main specs, and write the capability Purpose the archive leaves as a
placeholder so strict validation stays green.

openspec/specs/frontend-mall/spec.md

@@ -2,7 +2,9 @@
 
 ## Purpose
 The buyer-facing storefront: shell, home page, discovery, shopping and transaction flows, and the buyer center.
+
 ## Requirements
+
 ### Requirement: Localized storefront
 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.
 
@@ -151,3 +153,9 @@ Checkout SHALL offer the customer's saved addresses for selection, defaulting to
 - **WHEN** a signed-in shopper with saved addresses checks out
 - **THEN** the default address is preselected and the created order carries the chosen address
 
+### Requirement: Live customer account statistics
+The buyer-center dashboard and points surfaces SHALL load the signed-in customer's balance, frozen balance, currency, and points from the shared account API rather than `USER_STATS`.
+
+#### Scenario: account summary reload
+- **WHEN** a signed-in shopper reloads the buyer center
+- **THEN** displayed account statistics come from the selected API adapter and survive browser state loss