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/apps/collections/admin.py

@@ -0,0 +1,10 @@
+from django.contrib import admin
+
+from .models import Collection
+
+
+@admin.register(Collection)
+class CollectionAdmin(admin.ModelAdmin):
+    list_display = ["name", "owner", "document_count", "is_public", "created_at"]
+    list_filter = ["is_public"]
+    search_fields = ["name", "description"]

backend/apps/collections/models.py

@@ -0,0 +1,39 @@
+from django.conf import settings
+from django.db import models
+
+
+class Collection(models.Model):
+    """A user-created collection of documents."""
+    name = models.CharField(max_length=300)
+    description = models.TextField(blank=True, default="")
+    cover = models.ImageField(upload_to="collection_covers/", blank=True, null=True)
+    documents = models.ManyToManyField(
+        "documents.Document",
+        related_name="collections",
+        blank=True,
+    )
+    is_public = models.BooleanField(default=False)
+    owner = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        related_name="collections",
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        db_table = "collections_collection"
+        ordering = ["-updated_at"]
+
+    def __str__(self) -> str:
+        return self.name
+
+    @property
+    def document_count(self) -> int:
+        return self.documents.count()
+
+    @property
+    def cover_url(self) -> str | None:
+        if self.cover:
+            return self.cover.url
+        return None

backend/apps/collections/serializers.py

@@ -0,0 +1,33 @@
+from rest_framework import serializers
+
+from .models import Collection
+
+
+class CollectionSerializer(serializers.ModelSerializer[Collection]):
+    cover_url = serializers.SerializerMethodField()
+    document_count = serializers.IntegerField(read_only=True)
+
+    class Meta:
+        model = Collection
+        fields = [
+            "id", "name", "description", "cover_url", "document_count",
+            "is_public", "created_at", "updated_at",
+        ]
+        read_only_fields = ["id", "document_count", "created_at", "updated_at"]
+
+    def get_cover_url(self, obj: Collection) -> str | None:
+        return obj.cover_url
+
+
+class CollectionDetailSerializer(CollectionSerializer):
+    documents = serializers.PrimaryKeyRelatedField(many=True, read_only=True)
+
+    class Meta(CollectionSerializer.Meta):
+        fields = CollectionSerializer.Meta.fields + ["documents", "owner"]
+
+
+class CollectionDocumentActionSerializer(serializers.Serializer):
+    document_ids = serializers.ListField(
+        child=serializers.IntegerField(),
+        allow_empty=False,
+    )

backend/apps/collections/urls.py

@@ -0,0 +1,13 @@
+from django.urls import include, path
+from rest_framework.routers import DefaultRouter
+
+from . import views
+
+router = DefaultRouter()
+router.register("", views.CollectionViewSet, basename="collection")
+
+app_name = "collections"
+
+urlpatterns = [
+    path("", include(router.urls)),
+]

backend/apps/collections/views.py

@@ -0,0 +1,50 @@
+from rest_framework import permissions, status, viewsets
+from rest_framework.decorators import action
+from rest_framework.response import Response
+
+from apps.documents.models import Document
+
+from .models import Collection
+from .serializers import (
+    CollectionDetailSerializer,
+    CollectionDocumentActionSerializer,
+    CollectionSerializer,
+)
+
+
+class CollectionViewSet(viewsets.ModelViewSet):
+    """CRUD for user collections."""
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get_serializer_class(self):
+        if self.action in ("retrieve", "update", "partial_update"):
+            return CollectionDetailSerializer
+        return CollectionSerializer
+
+    def get_queryset(self):
+        return Collection.objects.filter(owner=self.request.user).prefetch_related("documents")
+
+    def perform_create(self, serializer):
+        serializer.save(owner=self.request.user)
+
+    @action(detail=True, methods=["post"])
+    def add_documents(self, request, pk=None):
+        """Add documents to a collection."""
+        collection = self.get_object()
+        serializer = CollectionDocumentActionSerializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+        docs = Document.objects.filter(
+            id__in=serializer.validated_data["document_ids"],
+            owner=request.user,
+        )
+        collection.documents.add(*docs)
+        return Response({"detail": f"Added {docs.count()} document(s)."}, status=status.HTTP_200_OK)
+
+    @action(detail=True, methods=["post"])
+    def remove_documents(self, request, pk=None):
+        """Remove documents from a collection."""
+        collection = self.get_object()
+        serializer = CollectionDocumentActionSerializer(data=request.data)
+        serializer.is_valid(raise_exception=True)
+        collection.documents.remove(*serializer.validated_data["document_ids"])
+        return Response({"detail": "Documents removed."}, status=status.HTTP_200_OK)