Clean up unused code and untrack build artifacts

- Remove dist/ from git (build output, already in .gitignore)
- Replace default React import with named StrictMode in main.jsx

https://claude.ai/code/session_01C4T3bYHR2svLq7JVcxKJ6Y

src/main.jsx

@@ -1,10 +1,10 @@
-import React from 'react';
+import { StrictMode } from 'react';
 import ReactDOM from 'react-dom/client';
 import App from './App.jsx';
 import './index.css';
 
 ReactDOM.createRoot(document.getElementById('root')).render(
-  <React.StrictMode>
+  <StrictMode>
     <App />
-  </React.StrictMode>
+  </StrictMode>
 );