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/users/page.tsx

@@ -0,0 +1,29 @@
+import { getUsers } from '@/app/actions/admin'
+import { CreateUserDialog } from '../create-user-dialog'
+import { UserList } from '../user-list'
+import { Plus } from 'lucide-react'
+import { Button } from '@/components/ui/button'
+
+export default async function AdminUsersPage() {
+  const users = await getUsers()
+
+  return (
+    <div className="space-y-6">
+      <div className="flex justify-between items-center">
+        <div>
+          <h1 className="text-3xl font-bold text-gray-900 dark:text-white">
+            Users
+          </h1>
+          <p className="text-gray-600 dark:text-gray-400 mt-1">
+            Manage application users and permissions
+          </p>
+        </div>
+        <CreateUserDialog />
+      </div>
+
+      <div className="bg-white dark:bg-zinc-900 rounded-lg shadow overflow-hidden border border-gray-200 dark:border-gray-800">
+        <UserList initialUsers={users} />
+      </div>
+    </div>
+  )
+}