fix(website): add AbortController to GitHub API fetch and 404 meta description

- Hero GitHubStarButton: add AbortController to abort fetch on unmount,
  preventing potential state updates on unmounted components
- not-found.tsx: add missing description metadata for SEO completeness

https://claude.ai/code/session_01XAKeP67mR8sb1MxDPkYhxC

Author: claude

website/src/app/not-found.tsx

@@ -3,6 +3,7 @@ import Link from 'next/link';
 
 export const metadata: Metadata = {
   title: '404 - Page Not Found',
+  description: 'The page you are looking for does not exist. Return to the GoSQLX homepage.',
   robots: { index: false, follow: false },
 };
 

website/src/components/home/Hero.tsx

@@ -12,10 +12,12 @@ function GitHubStarButton() {
   const [stars, setStars] = useState<number | null>(null);
 
   useEffect(() => {
-    fetch('https://api.github.com/repos/ajitpratap0/GoSQLX')
+    const controller = new AbortController();
+    fetch('https://api.github.com/repos/ajitpratap0/GoSQLX', { signal: controller.signal })
       .then((r) => r.json())
       .then((d) => { if (typeof d.stargazers_count === 'number') setStars(d.stargazers_count); })
       .catch(() => {});
+    return () => controller.abort();
   }, []);
 
   return (