v4.3.0: Books Settings & KCC 11

Books now have their own conversion controls, with safer output naming and an updated conversion stack.

Added

• Books settings card: everything dropped into Books_in now has its own settings card in the WebUI, exposing kepubify's conversion options: output extension, smarten punctuation, hyphenation, dummy titlepage, fullscreen reading fixes, custom CSS, find and replace, and charset override. Previously every one of these was hardcoded.
• Output extension for books: choose .kepub, the default and what Calibre and Calibre-Web-Automated expect, .kepub.epub, what a Kobo recognises over USB, or .epub for a conventional filename. All three options still run the book through kepubify and contain Kobo enhancements.

Fixed

• No KEPUB Extension no longer looks like it applies to books: the setting is a KCC option and only ever affected comics, but nothing in the UI said so, so ticking it and dropping an EPUB into Books_in looked like a bug. It is now labelled as comics only, and books have their own extension setting.
• Overlapping book folders fail safely: converted .epub and .kepub.epub files can be picked up as fresh input when either book folder contains the other. Bindery now rejects every overlapping layout in the WebUI and pauses book processing if it finds one in a hand-edited config, leaving source files untouched instead of converting them repeatedly.
• KCC settings match KCC 11: the landscape splitter now shows KCC's real Split, Rotate, and Split and rotate modes; obsolete controls that made conversions fail are gone; and KCC's current spread options and Kindle Paperwhite and Scribe profiles are available.

Changed

• Python 3.13 and KCC 11.0.1: the Docker image now runs both, with current runtime libraries and GitHub Actions. Existing saved KCC settings are migrated to the supported equivalents automatically.

Thanks to @tekgnosis-net for contributing the books settings work in #14.

Upgrading

Pull the latest image and restart. Existing settings keep the old .kepub behaviour by default. Before choosing .epub or .kepub.epub, make sure Books_in and Books_out are separate folders and neither one contains the other.