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/reader/apps.py

@@ -0,0 +1,7 @@
+from django.apps import AppConfig
+
+
+class ReaderConfig(AppConfig):
+    default_auto_field = "django.db.models.BigAutoField"
+    name = "apps.reader"
+    verbose_name = "Reader Settings"