feat: wave 2 migration (P3, P5, P7 openspec changes)

Implements, verifies, and archives the three remaining Wave 2 changes from
openspec/MIGRATION-PLAN.md.

- add-wallet-settlement (P3): demo recharge, guarded withdrawal freeze and
  one-time admin review, paginated own fund entries, idempotent per-shop
  weekly/monthly settlement statements with commission rate and one-time
  payout confirmation.
- add-merchant-onboarding (P5): personal/enterprise applications with one live
  application per user, guarded review with mandatory rejection reason, and
  transactional shop + owner provisioning returning one-time credentials;
  mall onboarding/status pages and an admin review console.
- add-membership-messaging (P7): platform member levels, append-only growth
  accrual on order completion with guarded one-way leveling, order/shipment/
  refund system messages with unread/read state and soft deletion, plus the
  mall header unread badge.

Backend: migrations 0019-0023, new wallet, settlement, merchant_onboarding,
membership and messaging modules, event hooks in order/fulfillment/aftersale,
and integration suites for each. Shared contract extended and all three
frontends updated; code indexes, domain docs, backend guidelines and the
migration tracker synced.

Verification: cargo test -p vmall-api green twice consecutively; mall, admin
and shop-admin builds pass; browser smoke on every new surface; openspec
validate --all --strict green (33 passed).

The three changes share the @vmall/shared contract, the mall mock adapter and
per-app locale/nav files, so they are committed together to keep every commit
buildable.

apps/mall/locales-extra.ts

@@ -12,6 +12,10 @@ import auth from "./locales/auth";
 import user from "./locales/user";
 import stores from "./locales/stores";
 import marketing from "./locales/marketing";
+import wallet from "./locales/wallet";
+import merchant from "./locales/merchant";
+import membership from "./locales/membership";
+import messaging from "./locales/messaging";
 
 type Tree = Record<string, unknown>;
 
@@ -42,7 +46,22 @@ const legacyZh: Tree = {
   },
 };
 
-const domains = [shell, home, search, product, cart, checkout, auth, user, stores, marketing];
+const domains = [
+  shell,
+  home,
+  search,
+  product,
+  cart,
+  checkout,
+  auth,
+  user,
+  stores,
+  marketing,
+  wallet,
+  merchant,
+  membership,
+  messaging,
+];
 
 export const enExtra: Tree = domains.reduce<Tree>(
   (acc, m) => deepMerge(acc, m.en as Tree),