fix: resolve React Error #310 and refactor admin section

- Fix React bug #33580: remove Suspense boundaries co-located with Link components
- Delete settings/loading.tsx and admin/loading.tsx (root cause of race condition)
- Convert all admin navigation from Next.js Link to anchor tags
- Move admin pages to dedicated (admin) route group
- Add AdminHeader matching main header visual design
- Add AdminSidebar with anchor-based navigation
- Add /api/admin/models route handler (replaces server actions for GET)
- Add /api/debug/client-error for server-side browser error reporting
- Add useNoteRefreshOptional() to fix crash in AdminHeader
- Hide Admin Dashboard menu for non-admin users
- Change app icons from yellow to blue (#3A7CA5) matching brand primary
- Fix admin search bar width to match main header

Made-with: Cursor

memento-note/app/(admin)/admin/page.tsx

@@ -0,0 +1,59 @@
+import { getUsers } from '@/app/actions/admin'
+import { AdminMetrics } from '@/components/admin-metrics'
+import { Users, Activity, Database, Zap } from 'lucide-react'
+
+export default async function AdminPage() {
+  const users = await getUsers()
+
+  // Mock metrics data - in a real app, these would come from analytics
+  const metrics = [
+    {
+      title: 'Total Users',
+      value: users.length,
+      trend: { value: 12, isPositive: true },
+      icon: <Users className="h-5 w-5 text-primary dark:text-primary-foreground" />,
+    },
+    {
+      title: 'Active Sessions',
+      value: '24',
+      trend: { value: 8, isPositive: true },
+      icon: <Activity className="h-5 w-5 text-green-600 dark:text-green-400" />,
+    },
+    {
+      title: 'Total Notes',
+      value: '1,234',
+      trend: { value: 24, isPositive: true },
+      icon: <Database className="h-5 w-5 text-purple-600 dark:text-purple-400" />,
+    },
+    {
+      title: 'AI Requests',
+      value: '856',
+      trend: { value: 5, isPositive: false },
+      icon: <Zap className="h-5 w-5 text-yellow-600 dark:text-yellow-400" />,
+    },
+  ]
+
+  return (
+    <div className="space-y-6">
+      <div>
+        <h1 className="text-3xl font-bold text-gray-900 dark:text-white">
+          Dashboard
+        </h1>
+        <p className="text-gray-600 dark:text-gray-400 mt-1">
+          Overview of your application metrics
+        </p>
+      </div>
+
+      <AdminMetrics metrics={metrics} />
+
+      <div className="bg-white dark:bg-zinc-900 rounded-lg shadow overflow-hidden border border-gray-200 dark:border-gray-800 p-6">
+        <h2 className="text-lg font-semibold text-gray-900 dark:text-white mb-4">
+          Recent Activity
+        </h2>
+        <p className="text-gray-600 dark:text-gray-400">
+          Recent activity will be displayed here.
+        </p>
+      </div>
+    </div>
+  )
+}