feat: add article page and not found component with markdown rendering

src/app/(pages)/article/[slug]/not-found.tsx

@@ -0,0 +1,22 @@
+import { Button } from '@/ui/components/shadcn/button';
+import { FileXIcon } from 'lucide-react';
+import Link from 'next/link';
+
+const ArticleNotFound = () => {
+    return (
+        <div className='flex flex-col items-center justify-center gap-4 py-24 text-center'>
+            <FileXIcon className='size-12 text-muted-foreground/40' />
+            <div>
+                <h1 className='text-2xl font-bold'>Article not found</h1>
+                <p className='mt-1 text-muted-foreground'>
+                    This article may have been moved or deleted.
+                </p>
+            </div>
+            <Button asChild variant='outline' size='sm'>
+                <Link href='/home'>Back to all articles</Link>
+            </Button>
+        </div>
+    );
+};
+
+export default ArticleNotFound;