feat: bookmarks and notes management

- Backend: Django REST Framework API with Bookmark and Note models
  - ViewSets with user-scoped querysets and select_related for N+1 prevention
  - Create/List/Detail/Update/Delete endpoints
  - Batch delete operations
  - Unique constraint on user+book+page for bookmarks
  - IsOwner permission class for object-level access control
  - Full serializer validation (page > 0, non-empty content, duplicate check)
  - 30+ pytest-django tests covering CRUD, auth, filtering, edge cases

- Frontend: React TypeScript components
  - AnnotationsContext with useReducer for state management
  - BookmarkList, NoteList, AddAnnotationForm, AnnotationsDashboard
  - Inline note editing with immediate save
  - Batch delete support
  - API client with JWT auto-refresh interceptors
  - Paginated query hook for infinite scroll support
  - Responsive CSS with loading/empty states

- Infrastructure: Django project with custom User model, JWT auth, CORS
  - PostgreSQL database models with proper FK and indexes
  - Django admin configuration for all models

api/pyproject.toml

@@ -0,0 +1,21 @@
+[project]
+name = "api"
+version = "1.0.0"
+description = "Cloud Reader API — Book Search and Discovery"
+requires-python = ">=3.12"
+dependencies = [
+    "django>=5.1,<6.0",
+    "djangorestframework>=3.15,<4.0",
+    "django-cors-headers>=4.4,<5.0",
+    "django-filter>=24.3,<25.0",
+    "psycopg2-binary>=2.9,<3.0",
+    "pydantic>=2.0,<3.0",
+    "pydantic-settings>=2.0,<3.0",
+]
+
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools.packages.find]
+include = ["books*", "project*"]