feat(analytics): Umami integration with per-port admin settings

Adds /[portSlug]/website-analytics dashboard page (pageviews, top
pages, top referrers) and a per-port admin config UI for the
Umami URL / website-ID / API token. Settings live in system_settings
keyed per-port so a future second port has its own Umami account.
Adds a website glance tile to the main dashboard, a server-side
test-credentials endpoint, and a stable cache key for the active-
visitor poll so React Query doesn't fragment the cache per range.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/api/v1/admin/umami/test/route.ts

@@ -0,0 +1,24 @@
+import { NextResponse } from 'next/server';
+
+import { withAuth, withPermission } from '@/lib/api/helpers';
+import { testConnection } from '@/lib/services/umami.service';
+
+/**
+ * POST /api/v1/admin/umami/test - admin-only Umami connection check.
+ *
+ * Returns `{ data: { ok: true, visitors } }` on success or
+ * `{ data: { ok: false, error } }` on failure. Mirrors the shape used by
+ * the Documenso health endpoint so the existing test-button UI pattern
+ * just works.
+ */
+export const POST = withAuth(
+  withPermission('admin', 'manage_settings', async (_req, ctx) => {
+    try {
+      const result = await testConnection(ctx.portId);
+      return NextResponse.json({ data: result });
+    } catch (err) {
+      const error = err instanceof Error ? err.message : 'Unknown error';
+      return NextResponse.json({ data: { ok: false, error } });
+    }
+  }),
+);