feat(xml): export device libraries as Rekordbox XML

[snkk2x-collab]

Closes #127.

Summary

• add document_from_device_export to build a DJ_PLAYLISTS document from PIONEER/rekordbox/export.pdb
• export collection metadata, file://localhost locations, TrackID-keyed playlists, beatgrid TEMPO entries, and cue POSITION_MARK entries from matching ANLZ files
• add rekordcrate export-xml <EXPORT_PATH> [OUTPUT_FILE] for writing the generated XML
• add fixture-based integration coverage over data/complete_export/demo_tracks
• add unit coverage for hot cue and memory loop serialization into Rekordbox POSITION_MARK elements, including Num, Type, Start, End, and unsupported hot cue filtering

Validation

• rustfmt src/pdb/mod.rs src/xml.rs src/main.rs tests/test_xml_export.rs
• cargo test

Notes

The repository fixture data does not include real hot cues in data/complete_export/demo_tracks, so the integration fixture primarily covers the full export path, track metadata, playlists, and beatgrid TEMPO entries. The added XML unit tests cover the hot cue and memory loop POSITION_MARK behavior directly.

I do not have access to a mid-2010s CDJ for the optional hardware/video proof described in #127, so this PR focuses on a deterministic implementation and test coverage inside the repository.

[acrilique]

I suggest doing any xml-related PRs against the xml-improvements branch (PR #130 ) and not main. Haven't reviewed this one entirely but there seems to be room for improvement.

[acrilique]

What's the point of these accessors? I don't see any advantage vs just making the fields public. They're currently not public just bc they aren't used anywhere afaik

[snkk2x-collab]

Addressed in 5d7e626: I removed the extra comment() / mix_name() accessors, made the corresponding TrackStrings fields public, and changed XML export to read track.offsets.comment / track.offsets.mix_name directly.

Validation: cargo test passes locally.

[snkk2x-collab]

Thanks for the direction. I retargeted this PR to xml-improvements and pushed a follow-up test commit covering exported position marks.

Current branch state:

• base: xml-improvements
• latest commits: c87293b feature implementation, 29815f3 XML export coverage
• local validation was run before the update and the new test coverage is included in src/xml.rs.

Ready for another review when you have time.

[snkk2x-collab]

Hi, I updated the PR to target the xml-improvements branch and verified the export tests locally. Before I spend more time adding hardware/import proof, can you confirm whether this PR is still eligible for the $200 bounty on #127 if accepted?