feat: monorepo structure with Django backend, React frontend, and Expo mobile app

- Backend: Django 5 + DRF with accounts, documents, collections, and reading apps
  - Custom User model with email-based auth, JWT via SimpleJWT
  - Full CRUD viewsets with ModelSerializer + DRF routers
  - pytest, Ruff, drf-spectacular (OpenAPI), whitenoise
  - Dockerfile for production deployment

- Frontend: React 18 + TypeScript + Vite
  - Lazy-loaded routes with ProtectedRoute/PublicRoute guards
  - Auth context with useReducer, token refresh interceptor
  - Pages: Login, Register, Library, Document Detail, Reader, Collections, Settings
  - Dark theme, responsive grid layout, Vite proxy to Django backend

- Mobile: Expo SDK 51 + React Native + Expo Router
  - File-based routing with login, register, and library screens
  - AsyncStorage for token persistence, token refresh interceptor
  - Shared API types via @cloud-reader/shared workspace package

- Shared: TypeScript types (API responses, auth, documents, etc.)
- CI/CD: 3 independent GitHub Actions pipelines (backend, frontend, mobile)

backend/.env.example

@@ -0,0 +1,15 @@
+# Cloud Reader Backend — Environment Variables
+# Copy to .env and fill in your values.
+
+SECRET_KEY=django-insecure-change-me-in-production
+DEBUG=True
+
+DB_ENGINE=django.db.backends.postgresql
+DB_NAME=cloud_reader
+DB_USER=cloud_reader
+DB_PASSWORD=cloud_reader
+DB_HOST=localhost
+DB_PORT=5432
+
+CORS_ALLOWED_ORIGINS=http://localhost:5173,http://localhost:3000
+ALLOWED_HOSTS=localhost,127.0.0.1