feat: update cookie paths for staff authentication and implement redirect logic in admin login

app/routes/_admin.lg-admin._auth.login.tsx

@@ -1,4 +1,17 @@
+import { redirect } from 'react-router'
+
+import { handleCookie } from '~/libs/cookies'
 import { AdminLoginPage } from '~/pages/admin-login'
 
+import type { Route } from './+types/_admin.lg-admin._auth.login'
+
+export const loader = async ({ request }: Route.LoaderArgs) => {
+  const { staffToken } = await handleCookie(request)
+
+  if (staffToken) {
+    throw redirect('/lg-admin')
+  }
+}
+
 const AuthLayout = () => <AdminLoginPage />
 export default AuthLayout