Remove old flutter code for React code

client/src/main.tsx

@@ -0,0 +1,13 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import App from './App';
+import '@fontsource/roboto/300.css';
+import '@fontsource/roboto/400.css';
+import '@fontsource/roboto/500.css';
+import '@fontsource/roboto/700.css';
+
+ReactDOM.createRoot(document.getElementById('root')).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>,
+);