Fix Lighthouse SEO metadata issues

app/(not-found)/[...not-found]/layout.tsx

@@ -18,8 +18,14 @@ const geistMono = Geist_Mono({
 });
 
 export const metadata: Metadata = {
-  title: "Create Next App",
-  description: "Generated by create next app",
+  metadataBase: new URL("https://opplenz.com"),
+  title: "Page Not Found | Opp lens",
+  description:
+    "Opp lens helps SMEs find relevant tenders, automate document handling, and get real-time alerts for new opportunities.",
+  robots: {
+    index: false,
+    follow: true,
+  },
   icons: {
     icon: "/fav-icon.svg",
   },