v0.8.6

Four package vocabularies that were never checked, and the first two EPUB
3.4 core media types.

Added

• image/avif and image/jxl are Core Media Types. Both are in EPUB
  3.4's core media types table (spec change log: AVIF 06-Oct-2025, JPEG XL
  23-Jan-2026), so a manifest item declaring either no longer needs a
  fallback and an <img> referencing one is no longer RSC-032. EPUB
  3.4's audio additions — Opus in an MP4 container, and the codec-bearing
  type for AAC LC — needed no change, since audio/mp4 was already
  accepted and the media-type parameter is stripped before comparison;
  they are now covered by a test so that cannot silently regress.

  This ships ahead of epubcheck, which has an open issue for AVIF and
  none for JXL. The practical difference: a publication targeting EPUB 3.3
  that uses AVIF draws a fallback error there and none here.

• Unknown package property names are now reported (OPF-027) in the
  four positions that had no vocabulary check at all. Manifest
  item/@properties was already checked; these are the rest:

  position	vocabulary
  meta/@property	the 16 unprefixed names, plus pageBreakSource (EPUB 3.4)
  meta/@property, media:	active-class, duration, narrator, playback-active-class
  itemref/@properties	page-spread-left/-right, plus the 18 rendition: overrides
  link/@rel	the 9 defined keywords

  A typo such as belongs-to-colection used to pass silently. A
  prefixed name is deliberately left alone — an author-declared prefix
  carries a vocabulary this tool cannot know, and an undeclared prefix
  is OPF-028, a different message. The five deprecated link/@rel
  keywords remain members of their vocabulary, so they keep drawing only
  their existing OPF-086 deprecation warning rather than gaining a
  second finding.

  EPUB 3 only: neither property nor itemref/@properties is an EPUB 2
  attribute, and the EPUB 2 package grammar already reports them.

Full notes: CHANGELOG.md. Also on crates.io.