feat(push): add Web Push (VAPID) for lock-screen notifications on iPad PWA

Task #554. Adds a full Web Push stack on top of the existing Socket.IO
notification fan-out so the iPad PWA (and any installed browser) receives
system notifications when Tx OS is closed or backgrounded.

Backend
- New `push_subscriptions` table (userId + unique endpoint + p256dh/auth
  keys + ua + timestamps), exported from `@workspace/db`.
- `artifacts/api-server/src/lib/push.ts`:
  - VAPID bootstrap from env, else cached file at LOCAL_STORAGE_ROOT
    (Docker volume) with /tmp fallback for Replit dev, else ephemeral.
  - `sendPushToUser()` honours `notificationsMuted` + per-channel prefs
    (orders/meetings/notes), prunes 404/410 endpoints, truncates payload
    bodies to ~3500 bytes.
  - **De-dup gate:** skips push when the user has any active Socket.IO
    connection (uses `io.in(\`user:\${uid}\`).fetchSockets()`), so a
    connected user only gets the in-app chime, never a duplicate system
    notification.
  - `upsertSubscription()` deletes a stale row first when the same
    browser endpoint flips to a different user (shared device) so the
    previous user's notifications can't leak.
- Four new routes: `GET /api/push/vapid-public-key`, `POST /api/push/subscribe`,
  `POST /api/push/unsubscribe`, and a spec-aligned alias
  `DELETE /api/push/subscribe?endpoint=...` (auth-gated, Zod-validated).
- Push hooked into 4 existing emit sites: service-orders `notifyUser`,
  notes new-note + reply, executive-meeting broadcast.

Frontend
- `artifacts/tx-os/public/sw.js`: push + notificationclick only (no
  asset caching). All URLs (icon, badge, navigation target) resolved
  against `self.registration.scope`, so the SW works at root or under
  a subpath without code changes.
- SW registration in `main.tsx` scoped to `BASE_URL`, gated on
  `serviceWorker` AND `PushManager` support so older browsers no-op
  cleanly.
- `use-push-subscription` hook (enable/disable/refresh + status).
- New `PushEnablePrompt` card mounted in `App` — appears on first
  launch when supported + permission still "default", one-tap enable,
  dismiss persists for 14 days. Silent on unsupported devices.
- `PushToggleRow` added inside Notification Settings.
- ar/en strings: `notifSettings.push.*` and `common.later`.

Plumbing
- OpenAPI: 3 new operations under `notifications`; orval codegen run.
- `docker-compose.yml` passes VAPID_PUBLIC_KEY / VAPID_PRIVATE_KEY /
  VAPID_SUBJECT through to the api service.
- `pnpm --filter @workspace/db run push` applied the schema.
- web-push + @types/web-push installed in api-server.

Verification
- API restarts clean; `/api/push/vapid-public-key` returns the key;
  subscribe endpoint 401s without auth.
- New `artifacts/api-server/tests/push.test.mjs` — 7/7 passing —
  covers VAPID endpoint, auth gating on subscribe/unsubscribe, row
  persistence + removal, idempotent re-subscribe with key rotation,
  account-switch endpoint reassignment, and malformed-input rejection.
- New `artifacts/api-server/tests/push-410-unit.test.ts` — 3/3
  passing — true in-process unit test (`node --import tsx
  --experimental-test-module-mocks`) that mocks `web-push` to verify
  the prune path: 410 deletes the row, 404 deletes the row, and a
  transient 500 leaves the row intact. `tsx` added as a devDep and the
  test:run script picks up `*.test.ts` alongside the existing `.mjs`
  suites.
- OpenAPI updated: `DELETE /push/subscribe` documented with an
  `endpoint` query parameter alongside the existing POST routes; orval
  codegen re-run so the generated client + zod schemas stay in sync.
- Restored the unrelated serial tests
  (`executive-meetings-notifications.test.mjs`, `setup-wizard.test.mjs`)
  that an earlier cleanup pass dropped — they are unchanged from prior
  green state.
- Architect rounds addressed:
  1. race + payload size.
  2. dedup gate + first-launch UX + SW base-path + initial tests.
  3. DELETE alias + PushManager check + restored serial tests + real
     410/404 cleanup test + OpenAPI parity.

pnpm-lock.yaml

@@ -46,7 +46,7 @@ catalogs:
       specifier: ^4.1.14
       version: 4.2.1
     tsx:
-      specifier: ^4.21.0
+      specifier: 4.21.0
       version: 4.21.0
     vite:
       specifier: ^7.3.2
@@ -196,6 +196,9 @@ importers:
       thread-stream:
         specifier: 3.1.0
         version: 3.1.0
+      tsx:
+        specifier: 'catalog:'
+        version: 4.21.0
 
   artifacts/mockup-sandbox:
     devDependencies: