The OPDS device catalog previously hard-coded every acquisition link as
application/epub+zip and always offered kepub/pdf alternate links, which
is wrong for comic archives (cbz/cbr/cb7/cbt) and other non-epub media.
- Resolve the acquisition mime type from the media item's stored
mime_type (falling back to format_mimetype, then epub) instead of
assuming epub
- Only offer reflowable conversions (kepub for kobo, pdf) for ebooks;
comic archives are served as-is in their native format
- Derive the native format label (epub/pdf/cbz/cbr/...) from the file
path in ListFormats rather than always reporting epub
- Add resolveMimeType, isComicArchive, and formatLabelFromPath helpers
john-okeefe
b1d2ccc87c