- Zoom buttons + Ctrl/Cmd +/-/0, Ctrl+wheel/trackpad pinch, touch pinch on PDFs;
PDF scales the pdf.js render (sharp re-render after it settles), EPUB scales text.
Remembered per format, and per book.
- One/two pages side by side: PDF rows with the cover alone, foliate max-column-count.
- Scroll vs Pages mode for both engines; PDF paged shows one page/spread fitted to the
screen, prev/next move a whole spread; spreads stack when scrolling.
- Reading position is kept across zoom/spread/mode changes; progress keeps saving.
- layout.ts helpers with unit tests; old flow/fontSize/pdfZoom settings migrate.
