Pavel Liashkov 0332e1103a Add EPUB 3 nav.xhtml TOC support (#197) ... ## Summary * **What is the goal of this PR?** Add EPUB 3 support by implementing native navigation document (nav.xhtml) parsing with NCX fallback, addressing issue Fixes: #143. * **What changes are included?** - New `TocNavParser` for parsing EPUB 3 HTML5 navigation documents (`<nav epub:type="toc">`) - Detection of nav documents via `properties="nav"` attribute in OPF manifest - Fallback logic: try EPUB 3 nav first, fall back to NCX (EPUB 2) if unavailable - Graceful degradation: books without any TOC now load with a warning instead of failing ## Additional Context * The implementation follows the existing streaming XML parser pattern using Expat to minimize RAM usage on the ESP32-C3 * EPUB 3 books that include both nav.xhtml and toc.ncx will prefer the nav document (per EPUB 3 spec recommendation) * No breaking changes - existing EPUB 2 books continue to work as before * Tested on examples from https://idpf.github.io/epub3-samples/30/samples.html		2026-01-03 19:10:35 +11:00
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Epub	Add EPUB 3 nav.xhtml TOC support (#197)	2026-01-03 19:10:35 +11:00
Epub.cpp	Add EPUB 3 nav.xhtml TOC support (#197)	2026-01-03 19:10:35 +11:00
Epub.h	Add EPUB 3 nav.xhtml TOC support (#197)	2026-01-03 19:10:35 +11:00