Add support for images in EPUB reading order

[mickael-menu]

Adds support for EPUBs with bitmap images directly in the spine, rendering them as Divina (fixed-layout) publications.

Added

Navigator

• Bitmap images in the EPUB reading order are now supported as a fixed layout resource.

Streamer

• EPUB manifest item fallbacks are now exposed as alternates in the corresponding Link.
• EPUBs with only bitmap images in the spine are now treated as Divina publications with fixed layout.
  • When an EPUB spine item is HTML with a bitmap image fallback (or vice versa), the image is preferred as the primary link.

Deprecated

Streamer

• The EPUB manifest item id attribute is no longer exposed in Link.properties.

Fixed

Navigator

• PDF documents are now opened off the main thread, preventing UI freezes with large files.

[Copilot]

Pull request overview

This pull request adds support for bitmap images in EPUB reading order by treating them as fixed-layout Divina publications. The changes enable EPUBs with images directly in the spine to render correctly using the fixed-layout navigator, with proper fallback handling and automatic Divina profile inference.

Changes:

• Enhanced EPUB parsing to handle fallback chains, preferring bitmap images over HTML when both are present
• Modified image-based publications to remove default center page property for covers
• Added async PDF document loading to prevent UI freezes with large files

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
Sources/Streamer/Parser/EPUB/OPFParser.swift	Implements fallback handling and Divina inference for image-based EPUBs
Sources/Streamer/Parser/EPUB/EPUBManifestParser.swift	Minor cleanup removing unused variable
Sources/Streamer/Parser/Image/ImageParser.swift	Removes automatic center page property assignment for first page
Sources/Navigator/PDF/PDFNavigatorViewController.swift	Adds async PDF document loading off main thread
Sources/Navigator/EPUB/Scripts/src/fixed-page.js	Adds bitmap image wrapping in HTML with accessibility support
Sources/Shared/Publication/Manifest.swift	Updates EPUB conformance check to use metadata instead of content type
Tests/StreamerTests/Parser/EPUB/OPFParserTests.swift	Adds comprehensive tests for fallback handling and Divina inference
Tests/StreamerTests/Parser/EPUB/EPUBManifestParserTests.swift	Updates tests to remove deprecated id property
Tests/StreamerTests/Parser/Image/ImageParserTests.swift	Updates test for center page property behavior
Multiple test fixture files	New OPF test fixtures for fallback scenarios
CHANGELOG.md	Documents new features, deprecations, and fixes

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