feat: adding frontend code (react)

frontend/src/App.tsx

@@ -0,0 +1,14 @@
+import React from 'react';
+
+// A simple functional component
+const App: React.FC = () => {
+  return (
+    <div>
+      <h1>Hello, world!</h1>
+      <p>Welcome to my React application. This is some test.</p>
+    </div>
+  );
+};
+
+
+export default App;