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)

mobile/app.json

@@ -0,0 +1,22 @@
+{
+  "expo": {
+    "name": "Cloud Reader",
+    "slug": "cloud-reader",
+    "version": "0.1.0",
+    "orientation": "portrait",
+    "icon": "./assets/icon.png",
+    "scheme": "cloudreader",
+    "userInterfaceStyle": "dark",
+    "splash": {
+      "backgroundColor": "#0f1419"
+    },
+    "ios": {
+      "supportsTablet": true,
+      "bundleIdentifier": "com.cloudreader.app"
+    },
+    "android": {
+      "package": "com.cloudreader.app"
+    },
+    "plugins": ["expo-router"]
+  }
+}