chore: moved exampled to frontend

frontend/examples/nextjs/components/HankoAuth.tsx

@@ -0,0 +1,31 @@
+import { register } from "@teamhanko/hanko-elements";
+import { useCallback, useEffect } from "react";
+import { useRouter } from "next/router";
+
+const api = process.env.NEXT_PUBLIC_HANKO_API!;
+
+interface Props {
+  setError(error: Error): void;
+}
+
+function HankoAuth({ setError }: Props) {
+  const router = useRouter();
+
+  const redirectToTodos = useCallback(() => {
+    router.replace("/todo").catch(setError);
+  }, [router, setError]);
+
+  useEffect(() => {
+    register({ shadow: true }).catch(setError);
+  }, [setError]);
+
+  useEffect(() => {
+    document.addEventListener("hankoAuthSuccess", redirectToTodos);
+    return () =>
+      document.removeEventListener("hankoAuthSuccess", redirectToTodos);
+  }, [redirectToTodos]);
+
+  return <hanko-auth api={api} />;
+}
+
+export default HankoAuth;