Rebuild the app and read-aloud worker images on Node 26.12.1, which fixes
CVE-2026-111497 in the bundled Brotli decoder and the other October 2026
Node security issues. The app image stays on Alpine 3.23, pinned by digest.
Closes#1912
Generate a synced read-aloud EPUB from a book's EPUB and audiobook through an
optional STAlign worker (Docker on CPU, or native with MLX on Apple Silicon),
with review, re-sync, replace in place, restart recovery and live progress on
the Files tab. Book details also stack the ebook and audiobook covers when
both exist. See docs/READ_ALOUD.md.