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/.env.example

@@ -0,0 +1,2 @@
+VITE_API_URL=http://localhost:3000
+