Finalize diagnostics, logging controls, and email test support

frontend/app/admin/diagnostics/page.tsx

@@ -0,0 +1,27 @@
+'use client'
+
+import AdminShell from '../../ui/AdminShell'
+import AdminDiagnosticsPanel from '../../ui/AdminDiagnosticsPanel'
+
+export default function AdminDiagnosticsPage() {
+  return (
+    <AdminShell
+      title="Diagnostics"
+      subtitle="Run connectivity, delivery, and platform health checks for every configured dependency."
+      rail={
+        <div className="admin-rail-stack">
+          <div className="admin-rail-card">
+            <span className="admin-rail-eyebrow">Diagnostics</span>
+            <h2>Shared console</h2>
+            <p>
+              This page and Maintenance now use the same diagnostics panel, so every test target and
+              notification ping stays in one source of truth.
+            </p>
+          </div>
+        </div>
+      }
+    >
+      <AdminDiagnosticsPanel />
+    </AdminShell>
+  )
+}