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/pages/user/index.vue

@@ -134,6 +134,23 @@ const statusLinks = computed(() => [
           ><b class="text-primary text-lg font-semibold">{{ item.count }}</b></NuxtLink
         >
       </div>
+      <nav class="border-border flex flex-wrap items-center gap-x-6 gap-y-2 border-t py-3">
+        <NuxtLink
+          class="text-primary hover:text-primary-hover text-sm no-underline"
+          to="/user/wallet"
+          >{{ t("wallet.title") }} ›</NuxtLink
+        >
+        <NuxtLink
+          class="text-primary hover:text-primary-hover text-sm no-underline"
+          to="/user/membership"
+          >{{ t("membership.title") }} ›</NuxtLink
+        >
+        <NuxtLink
+          class="text-primary hover:text-primary-hover text-sm no-underline"
+          to="/user/messages"
+          >{{ t("messaging.title") }} ›</NuxtLink
+        >
+      </nav>
     </VCard>
 
     <VCard>