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/settings/page.tsx

@@ -0,0 +1,23 @@
+import { getSystemConfig } from '@/app/actions/admin-settings'
+import { AdminSettingsForm } from './admin-settings-form'
+
+export default async function AdminSettingsPage() {
+  const config = await getSystemConfig()
+
+  return (
+    <div className="space-y-6">
+      <div>
+        <h1 className="text-3xl font-bold text-gray-900 dark:text-white">
+          Settings
+        </h1>
+        <p className="text-gray-600 dark:text-gray-400 mt-1">
+          Configure application-wide settings
+        </p>
+      </div>
+
+      <div className="bg-white dark:bg-zinc-900 rounded-lg shadow overflow-hidden border border-gray-200 dark:border-gray-800 p-6">
+        <AdminSettingsForm config={config} />
+      </div>
+    </div>
+  )
+}