feat(admin-console): Stage 2 — dashboard monitoring

Turn the console landing page into an operational dashboard.

- new internal/opsstatus: read-only Postgres projection via go-jet — ping +
  per-status COUNT/GROUP BY on runtime_records, mail_deliveries,
  notification_routes, and a malformed-intent count; degrades per-probe into
  Snapshot.Errors rather than failing the page
- dashboard renders backend readiness, database health, the three status
  tables, the malformed count, and any collection errors; falls back to a
  "monitoring not wired" note when no reader is injected
- AdminConsoleHandlers now takes an AdminConsoleDeps struct (Monitor + Ready
  added) so later stages add service refs without churning the signature

Tests: opsstatus store test against a Postgres testcontainer (empty schema +
one enqueued delivery); dashboard render tests with a fake reader (with and
without monitoring).

Docs: ARCHITECTURE 14.1 + FUNCTIONAL 10.2.1 (+ru) describe the dashboard.
(Prometheus /metrics exporters were already enabled in dev-deploy in Stage 1.)

docs/ARCHITECTURE.md

@@ -602,7 +602,13 @@ only the edge anti-abuse layer.
 State-changing requests are guarded against CSRF by a stateless token
 (HMAC-SHA256 over the authenticated username, keyed by
 `BACKEND_ADMIN_CONSOLE_CSRF_KEY`; a per-process random key is used when the
-variable is unset) plus a same-origin `Origin`/`Referer` check. See
+variable is unset) plus a same-origin `Origin`/`Referer` check.
+
+The console landing page is a dashboard that surfaces backend-visible
+operational signals — database reachability, per-status game-runtime counts,
+and mail/notification queue depths — read directly through the persistence
+layer; richer historical metrics come from the Prometheus exporters on
+`backend` and `gateway` (see [§17](#17-observability)). See
 `backend/docs/admin-console.md` for the console design.
 
 ## 15. Transport Security Model (gateway boundary)

docs/FUNCTIONAL.md

@@ -1178,6 +1178,12 @@ limiting and request limits as the public API, and it carries an
 anti-CSRF token on every change. The JSON admin API stays internal to
 the deployment.
 
+The console landing page is a dashboard that summarises operational
+health: whether the backend is ready and the database reachable, how many
+game runtimes sit in each state, and the depth of the mail and
+notification queues. It is a read-only point-in-time view for quick
+triage, not a metrics history.
+
 ### 10.3 Admin account management
 
 Existing admins can list other admins, create new ones, look up a

docs/FUNCTIONAL_ru.md

@@ -1214,6 +1214,12 @@ admin-API, либо через серверно-рендеримую веб-ко
 анти-CSRF-токен на каждом изменении. JSON admin-API остаётся
 внутренним для деплоя.
 
+Стартовая страница консоли — дашборд, сводящий операционное
+здоровье: готов ли backend и доступна ли БД, сколько игровых рантаймов
+в каждом состоянии, какова глубина очередей почты и уведомлений. Это
+read-only-срез на текущий момент для быстрой диагностики, не история
+метрик.
+
 ### 10.3 Управление admin-аккаунтами
 
 Существующие админы могут перечислять других админов, создавать