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.

openspec/specs/aftersale/spec.md

@@ -1,7 +1,10 @@
 # aftersale Specification
 
 ## Purpose
-TBD - created by archiving change add-aftersale-refunds. Update Purpose after archive.
+Post-purchase after-sale handling: per-line refund-only and return-refund
+applications, merchant processing, bilateral messages, and platform
+arbitration. A completed refund updates the order's refund total and credits
+the customer's available account with a ledger entry in one transaction.
 ## Requirements
 ### Requirement: Per-line aftersale application
 An authenticated customer SHALL apply for after-sale against one owned order item from an order that is paid or shipped and within the configured after-sale window. The application SHALL choose exactly `refund_only` or `return_refund`, include a localized reason, an integer minor-unit refund amount greater than zero and no greater than the line's remaining refundable amount, and zero or more evidence image URLs. The API SHALL reject unavailable, already fully refunded, out-of-window, or cross-customer items.