## Summary
* Rely on media-type="application/x-dtbncx+xml" to find TOC instead of
hardcoded values
## Additional Context
* Most of my epubs don't have id==ncx for toc file location. I think
this media-type is EPUB standard
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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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