fix: update not found handling in GET route to return 404 response

apps/wiki/app/llms.mdx/[[...slug]]/route.ts

@@ -1,13 +1,12 @@
 import {getLLMText} from '@/lib/get-llm-text';
 import {source} from '@/lib/source';
-import {notFound} from 'next/navigation';
 
 export const revalidate = false;
 
 export async function GET(_req: Request, props: {params: Promise<{slug?: string[]}>}) {
   const params = await props.params;
   const page = source.getPage(params.slug);
-  if (!page) notFound();
+  if (!page) return new Response('Not found', {status: 404});
 
   return new Response(await getLLMText(page), {
     headers: {