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.)

backend/internal/adminconsole/assets/console.css

@@ -47,3 +47,25 @@ h1 { font-size: 1.4rem; margin: 0 0 0.4rem; }
 .card:hover { background: var(--panel-hi); text-decoration: none; }
 .card h2 { font-size: 1.05rem; margin: 0 0 0.3rem; color: var(--accent); }
 .card p { margin: 0; color: var(--ink-dim); font-size: 0.9rem; }
+
+.panel {
+  padding: 0.9rem 1.1rem;
+  background: var(--panel);
+  border: 1px solid var(--line);
+  border-radius: 8px;
+  margin-bottom: 1rem;
+}
+.panel h2 { font-size: 1rem; margin: 0 0 0.6rem; color: var(--ink); }
+.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 1rem; margin-bottom: 1rem; }
+.grid .panel { margin-bottom: 0; }
+.kv { list-style: none; margin: 0; padding: 0; }
+.kv li { padding: 0.15rem 0; color: var(--ink-dim); }
+.counts { width: 100%; border-collapse: collapse; font-size: 0.9rem; }
+.counts td { padding: 0.2rem 0; border-bottom: 1px solid var(--line); color: var(--ink-dim); }
+.counts td.num { text-align: right; color: var(--ink); font-variant-numeric: tabular-nums; }
+.bignum { font-size: 1.6rem; margin: 0; color: var(--ink); }
+.note { color: var(--ink-dim); font-style: italic; margin: 0.2rem 0; }
+.errors { border-color: var(--danger); }
+.errors ul { margin: 0; padding-left: 1.1rem; color: var(--danger); }
+.ok { color: var(--ok); }
+.bad { color: var(--danger); }

backend/internal/adminconsole/dashboard.go

@@ -0,0 +1,24 @@
+package adminconsole
+
+// StatusCount pairs a status label with its current row count for the
+// dashboard's per-status tables. It is the view-layer counterpart of the
+// data gathered by the ops-status reader; the server handler maps between
+// them so this package stays free of database concerns.
+type StatusCount struct {
+	Status string
+	Count  int64
+}
+
+// DashboardData is the view model for the console landing page. MonitorAvailable
+// is false when no ops-status reader is wired, in which case the monitoring
+// panels are omitted. Errors carries non-fatal probe failures for display.
+type DashboardData struct {
+	MonitorAvailable      bool
+	BackendReady          bool
+	PostgresHealthy       bool
+	Runtimes              []StatusCount
+	MailDeliveries        []StatusCount
+	NotificationRoutes    []StatusCount
+	NotificationMalformed int64
+	Errors                []string
+}

backend/internal/adminconsole/templates/pages/dashboard.gohtml

@@ -1,6 +1,43 @@
 {{define "content" -}}
 <h1>Dashboard</h1>
 <p class="lede">Signed in as <strong>{{.Username}}</strong>.</p>
+{{with .Data}}
+<section class="panel">
+  <h2>Health</h2>
+  <ul class="kv">
+    <li>Backend ready: {{if .BackendReady}}<span class="ok">yes</span>{{else}}<span class="bad">no</span>{{end}}</li>
+    <li>Postgres: {{if .PostgresHealthy}}<span class="ok">healthy</span>{{else}}<span class="bad">unreachable</span>{{end}}</li>
+  </ul>
+</section>
+{{if .MonitorAvailable}}
+<div class="grid">
+  <section class="panel">
+    <h2>Game runtimes</h2>
+    {{template "statuscounts" .Runtimes}}
+  </section>
+  <section class="panel">
+    <h2>Mail deliveries</h2>
+    {{template "statuscounts" .MailDeliveries}}
+  </section>
+  <section class="panel">
+    <h2>Notification routes</h2>
+    {{template "statuscounts" .NotificationRoutes}}
+  </section>
+  <section class="panel">
+    <h2>Malformed notifications</h2>
+    <p class="bignum {{if gt .NotificationMalformed 0}}bad{{end}}">{{.NotificationMalformed}}</p>
+  </section>
+</div>
+{{if .Errors}}
+<section class="panel errors">
+  <h2>Collection errors</h2>
+  <ul>{{range .Errors}}<li>{{.}}</li>{{end}}</ul>
+</section>
+{{end}}
+{{else}}
+<p class="note">Monitoring is not wired in this deployment.</p>
+{{end}}
+{{end}}
 <section class="cards">
   <a class="card" href="/_gm/users">
     <h2>Users</h2>
@@ -20,3 +57,13 @@
   </a>
 </section>
 {{- end}}
+
+{{define "statuscounts" -}}
+{{if .}}
+<table class="counts"><tbody>
+{{range .}}<tr><td>{{.Status}}</td><td class="num">{{.Count}}</td></tr>{{end}}
+</tbody></table>
+{{else}}
+<p class="note">none</p>
+{{end}}
+{{- end}}