refactor(MyForm): add onSubmit prop for Storybook actions integration

src/stories/myForm.tsx

@@ -1,14 +1,22 @@
-import React from "react";
 import { useForm } from "@tanstack/react-form";
 
-export function MyForm() {
+interface MyFormProps {
+  onSubmit?: (values: {
+    username?: string;
+    age?: string;
+    password?: string;
+  }) => void;
+}
+export function MyForm({ onSubmit }: MyFormProps) {
   const form = useForm({
     defaultValues: {
       username: "",
       age: "",
       password: "",
     },
+
     onSubmit: async ({ value }) => {
+      onSubmit?.(value);
       console.log("Form submitted successfully:", value);
       alert(JSON.stringify(value, null, 2));
     },