- Implement custom previous/next page buttons for EPUB viewer.
- Display current page number out of total pages.
- Introduce an in-viewer, toggleable table of contents (TOC) for quick chapter navigation.
- Hide default `react-reader` navigation arrows and title bar to prevent redundancy.
- Adjust `react-reader` styles to optimize content area and ensure custom controls are visible.
- Update description for EPUB theme setting in document settings.
- Add `ChevronLeftIcon` and `ChevronRightIcon` to icon library.
- Update Playwright tests to reflect new navigation button labels.