feat: customizable mobile reading experience

- Backend: Chapter, ReadingProgress, ReadingSettings models
- Backend: Chapter API (TOC + content), progress tracking, settings CRUD
- Frontend: ReadingPage with chapter navigation
- Frontend: TableOfContents drawer
- Frontend: ReadingSettingsPanel (theme, font, size, orientation)
- Frontend: Custom hooks for settings, chapters, progress tracking
- CSS: Mobile-first reading view with sepia/dark/light/paper themes
- Route: /reader/:bookId reading view from book detail page
- Docs: 001-customizable-mobile-reading-experience.md

backend/apps/books/views.py

@@ -1,16 +1,25 @@
 from django_filters.rest_framework import DjangoFilterBackend
-from rest_framework import viewsets
+from rest_framework import status, viewsets
+from rest_framework.decorators import action
 from rest_framework.filters import OrderingFilter, SearchFilter
 from rest_framework.permissions import IsAuthenticated
+from rest_framework.request import Request
+from rest_framework.response import Response
 
-from apps.books.models import Book
-from apps.books.serializers import BookListSerializer, BookSerializer
+from apps.books.models import Book, Chapter, ReadingProgress
+from apps.books.serializers import (
+    BookListSerializer,
+    BookSerializer,
+    ChapterDetailSerializer,
+    ChapterSummarySerializer,
+    ReadingProgressSerializer,
+)
 
 
 class BookViewSet(viewsets.ModelViewSet):
-    """CRUD for books."""
+    """CRUD for books. Includes nested chapter and progress endpoints."""
 
-    queryset = Book.objects.all()
+    queryset = Book.objects.all().prefetch_related("chapters")
     permission_classes = [IsAuthenticated]
     filter_backends = [DjangoFilterBackend, SearchFilter, OrderingFilter]
     filterset_fields = ["author"]
@@ -21,4 +30,46 @@ class BookViewSet(viewsets.ModelViewSet):
     def get_serializer_class(self):
         if self.action == "list":
             return BookListSerializer
-        return BookSerializer
+        return BookSerializer
+
+    @action(detail=True, methods=["get"])
+    def chapters(self, request: Request, pk: int | None = None) -> Response:
+        """List all chapters for this book (TOC)."""
+        book = self.get_object()
+        chapters = book.chapters.all().order_by("number")
+        serializer = ChapterSummarySerializer(chapters, many=True)
+        return Response(serializer.data)
+
+    @action(detail=True, methods=["get"], url_path="chapters/(?P<chapter_number>[0-9]+)")
+    def chapter_detail(
+        self, request: Request, pk: int | None = None, chapter_number: str | None = None
+    ) -> Response:
+        """Get a specific chapter with full content."""
+        book = self.get_object()
+        try:
+            chapter = book.chapters.get(number=int(chapter_number))
+        except Chapter.DoesNotExist:
+            return Response(
+                {"detail": "Chapter not found."}, status=status.HTTP_404_NOT_FOUND
+            )
+        serializer = ChapterDetailSerializer(chapter)
+        return Response(serializer.data)
+
+    @action(detail=True, methods=["get", "put"])
+    def progress(self, request: Request, pk: int | None = None) -> Response:
+        """Get or update reading progress for this book."""
+        book = self.get_object()
+        progress, created = ReadingProgress.objects.get_or_create(
+            user=request.user, book=book
+        )
+
+        if request.method == "GET":
+            serializer = ReadingProgressSerializer(progress)
+            return Response(serializer.data)
+
+        serializer = ReadingProgressSerializer(
+            progress, data=request.data, partial=True
+        )
+        serializer.is_valid(raise_exception=True)
+        serializer.save()
+        return Response(serializer.data, status=status.HTTP_200_OK)