- Implement PlaylistEntry wrapper for PlaylistItem proto (23 tests, 40 assertions)
- Support all 4 item types: header, presentation, placeholder, cue
- Expose arrangement_name (field 5) for presentation items
- Type-specific getters with null safety
- Implement PlaylistNode wrapper for Playlist proto (15 tests, 37 assertions)
- Handle both container nodes (child playlists) and leaf nodes (items)
- Recursive wrapping of nested playlist structures
- Implement PlaylistArchive wrapper for PlaylistDocument proto (18 tests, 37 assertions)
- Top-level integration of nodes, entries, and embedded files
- Lazy parsing of embedded .pro files into Song objects
- File partitioning: .pro files vs media files
Wave 2 of proplaylist-module plan complete (Tasks 4-6)
