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)

.gitignore

@@ -0,0 +1,48 @@
+# Python
+__pycache__/
+*.py[cod]
+*.egg-info/
+dist/
+build/
+.eggs/
+*.egg
+.env
+venv/
+.venv/
+*.sqlite3
+
+# Node
+node_modules/
+.pnp
+.pnp.js
+yarn-error.log*
+
+# Build artifacts
+dist/
+build/
+*.tsbuildinfo
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+.DS_Store
+
+# Django
+backend/media/
+backend/staticfiles/
+backend/**/migrations/
+
+# Expo / React Native
+mobile/.expo/
+mobile/ios/Pods/
+mobile/android/.gradle/
+mobile/android/app/build/
+mobile/android/build/
+mobile/*.hprof
+
+# Environment
+.env.local
+.env.production
+.env.development