CBZ reader frequently skips pages while reading #2402

What went wrong?

In the CBX reader, reading a comic in infinite scroll mode, the view abruptly jumps
backward after scrolling through roughly 10-15 pages — landing back near the page the
book was opened on, as if reading progress got reloaded and overwrote the current
scroll position.

How can we reproduce it?

1. Open a CBZ with 50+ pages.
2. Switch to infinite scroll mode.
3. Scroll continuously downward through ~10-15 pages without stopping.

What happened: the reader jumps back to (approximately) the page it opened on.
What you expected: smooth continuous scrolling, with reading progress reflecting the
current page.

Note: same symptom as booklore-app/booklore#2777, reported for the same reader in this
project's upstream.

What Build of Grimmory are you on?

Nightly

Your setup

• Grimmory version: develop (local build via dev.docker-compose.yml)
• How you're running it: Docker
• Browser: Firefox
• Operating system: Arch Linux

Screenshots or error messages (optional)

No response

Before submitting

• I've searched existing issues and discussions and this hasn't been reported yet
• I've reviewed this report and have completed it as fully as I can