EPUB cover previews and sort

[eric-morrison]

Summary

This adds a lightweight cover-preview experience to the browser UI for Pixel Reader on Onion/Miyoo Mini+, as well as the ability to sort by title or author.

What Changed

• add EPUB cover extraction for browser preview
• parse EPUB title and author metadata for browser display
• show two-line browser rows with title and author
• add sort toggle between title and author
• add right-side cover preview pane
• show a lightweight loading state while browser metadata indexes
• show selected-book progress in the preview pane
• fix an EPUB cleanup crash triggered during browser metadata loading
• make async task queue access thread-safe
• link pthread for the preview/index worker path

Notes

This improves the browsing experience a lot, but it does introduce some extra work when opening large book folders because metadata is indexed for sorting/display. The current implementation keeps the loading state lightweight and avoids full-library progress scanning during that step, but there is still room for future performance tuning if needed. I tested with 300+ EPUB files and it took a couple seconds to load.

Testing

• built Onion/Miyoo packages successfully via the cross-compile Docker toolchain
• tested on-device manually for:
  • right-side cover previews
  • title/author browser rows
  • title/author sort toggle
  • loading-state behavior
  • selected-book progress display

[ealang]

Thanks! Let me spend a few days to try this out