feat(push): M7 backend — opt-in push notifications via self-hosted ntfy

Additive, v1-only backend contract for the Android app's opt-in push (Part 1 of
M7; docs/android/PLAN.md §11). The app is a pure consumer — this lands the
endpoints, fan-out, and relay it needs.

- Schema: push_devices (per-device endpoint) + notification_subscriptions
  (per-user opted-in streams), FK→users ON DELETE CASCADE.
- Stream catalog + event→stream mapping (config/notificationStreams.js): public
  streams (news.post, server.status, idoc.warning, champ.start, governor.election)
  drawn ONLY from the SSE PUBLIC_KINDS allowlist; personal owner-keyed streams
  (vendor.sale, house.idoc, account.login). Full-state upserts (champ/city) fire
  only on a real transition via an injectable tracker.
- Fan-out (utils/pushDispatch.js): content-free tickles ({ stream, ref }) POSTed
  to each subscribed device; never throws. Two producers — shardIngest.ingest
  (beside the SSE broadcast) and the create/publish-post path (news.post).
  Personal events resolve to the owner via shardLinks. SSRF guard: endpoints must
  be HTTPS, non-private, and on the NTFY_BASE_URL/NTFY_ALLOWED_ORIGINS allow-set —
  enforced at registration and every publish.
- Routes under the role-agnostic self surface (never /admin): POST|GET
  /auth/me/devices, DELETE /auth/me/devices/:id, GET
  /auth/me/notifications/streams, GET|PUT /auth/me/notifications/subscriptions.
  Swagger regenerated (4 paths, PushDevice/NotificationStreams/etc. schemas).
- ntfy service in docker-compose.yml: pinned image, declarative ./ntfy/server.yml,
  no published host port, anonymous unguessable topics (no accounts) — zero
  interactive setup. No publish token required (content-free design); optional
  NTFY_PUBLISH_TOKEN honored.
- Tests: pushDispatch (mapping, PUBLIC_KINDS gate, owner-keying, SSRF guard,
  content-free payload) + notifications route auth gate. Full suite green (247).

Co-Authored-By: Claude <noreply@anthropic.com>

server/src/router/v1/auth/auth.routes.js

@@ -17,6 +17,7 @@ const validate = require('../../../middleware/validate')
 const mobileRouter = require('./mobile.routes')
 const ssoRouter = require('./sso.routes')
 const meRouter = require('./me.routes')
+const notifRouter = require('./notifications.routes')
 
 const authRouter = express.Router()
 
@@ -34,6 +35,11 @@ authRouter.use(ssoRouter)
 // free route, so /me falls through to its own handler).
 authRouter.use('/me', meRouter)
 
+// Push-notification self-service — /auth/me/devices*, /auth/me/notifications/*.
+// A second sub-router at /me (Express allows multiple), same requireAuth gate,
+// keeping the notification surface separate from the account/identity handlers.
+authRouter.use('/me', notifRouter)
+
 // Login protection order (cheapest rejection first):
 //   backoffGuard → per-IP exponential lockout on repeated failures
 //   slowLogin    → progressive per-request delay within the window