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/shipping/spec.md

@@ -1,7 +1,9 @@
 # shipping Specification
 
 ## Purpose
-TBD - created by archiving change add-freight-templates. Update Purpose after archive.
+Merchant-owned freight templates (by piece or by weight, with region rules and
+a default per shop) plus the platform shipping-company dictionary, used by
+server-side checkout pricing of per-shop shipping fees.
 ## Requirements
 ### Requirement: Merchant freight template management
 Shop users SHALL manage freight templates for their own shop only, scoped through `own_shop`, and platform administrators SHALL manage none implicitly. A template SHALL have a name, an optional always-free toggle, a pricing method of `by_piece` or `by_weight`, first-unit and additional-unit fees in i64 minor units of the shop currency, integer first/additional unit sizes (pieces for `by_piece`, grams for `by_weight`), and an optional free-shipping threshold in i64 minor units. At most one template per shop SHALL be the default, enforced by the database and preserved under concurrent default changes with guarded updates. Amounts SHALL be i64 minor units and weights integer grams; floating-point money is forbidden. Services SHALL return `ApiResult<Dto>`.