Add AudioBookshelf Support

[EddieDover]

Fixes #69

[github-actions]

✅ Code Coverage Report

Overall Coverage: 85%
Threshold: 85%
Status: PASS

✅ Coverage meets the required threshold!

📁 Coverage by File

File	Coverage	Status
src/app.rs	72% ██████████████░░░░░░	⚠️
src/mpris.rs	79% ███████████████░░░░░	⚠️
src/test_utils.rs	84% ████████████████░░░░	⚠️
src/config.rs	85% █████████████████░░░	✅
src/ui.rs	90% ██████████████████░░	✅
src/radio.rs	96% ███████████████████░	✅
src/audio.rs	96% ███████████████████░	✅
src/app/tests_delete.rs	97% ███████████████████░	✅
src/app/tests_edit.rs	97% ███████████████████░	✅
src/subsonic.rs	99% ███████████████████░	✅
src/audiobookshelf.rs	99% ███████████████████░	✅
src/favorites.rs	100% ████████████████████	✅
src/radio/tests_export.rs	100% ████████████████████	✅

Summary: 13 files analyzed | ⚠️ 3 file(s) below threshold

How to improve coverage

1. Run locally: cargo llvm-cov --html
2. Open coverage/html/index.html to see uncovered lines
3. Focus on files with ⚠️ - they need more tests
4. Add tests for uncovered code paths
5. Re-run: cargo test to verify

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Coverage report updated on each commit