chore: add client/src/pages/not-found.tsx

client/src/pages/not-found.tsx

@@ -0,0 +1,12 @@
+import { Link } from "wouter";
+
+export default function NotFound() {
+  return (
+    <div className="min-h-[60vh] flex flex-col items-center justify-center text-center px-4">
+      <h1 className="text-6xl font-bold text-muted-foreground/30 mb-4">404</h1>
+      <h2 className="text-2xl font-bold mb-3">Page not found</h2>
+      <p className="text-muted-foreground mb-6">The page you're looking for doesn't exist.</p>
+      <Link href="/" className="text-primary hover:underline">← Back to shop</Link>
+    </div>
+  );
+}