Initial project setup: monorepo structure with frontend and backend

- Set up pnpm workspace with frontend (React + Vite) and backend (Express + Prisma)
- Configure TypeScript, ESLint, and Prettier
- Add Prisma schema for database models (User, Course, Lesson, Progress, etc.)
- Create basic frontend structure with Tailwind CSS and shadcn/ui
- Add environment configuration files
- Update README with project overview and setup instructions
- Complete Phase 0: Project initialization

packages/frontend/src/main.tsx

@@ -0,0 +1,11 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import App from './App.tsx';
+import './index.css';
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+);
+