Playlist abstract

[semohr]

Refactor the playlist class hierarchy by renaming PlaylistCollection to Playlist and introducing dedicated abstractions for different playlist use cases (offline, remote-synced, multi-request remote).

Motivation
The previous PlaylistCollection class had grown to handle too many responsibilities:

• Minimal playlist protocol (info, tracks, ids)
• In-memory/offline playlists
• Remote synchronization lifecycle
• Multi-request API operations
  This refactoring separates these concerns into distinct classes with clearer roles.

New hierachy

TODOs:

• Fix TODO comments in core/playlist.py
• Migrate services to new format
• Migrate examples
• Migrate notebooks

closes #78
closes #62

[github-actions]

Thank you for the PR! The changelog has not been updated, so here is a friendly reminder to check if you need to add an entry.

[codecov]

Codecov Report

❌ Patch coverage is 73.41040% with 92 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
plistsync/services/tidal/playlist.py	61.36%	13 Missing and 4 partials ⚠️
plistsync/services/tidal/library.py	36.00%	12 Missing and 4 partials ⚠️
plistsync/services/spotify/library.py	31.81%	10 Missing and 5 partials ⚠️
plistsync/services/plex/playlist.py	70.21%	13 Missing and 1 partial ⚠️
plistsync/services/plex/library.py	52.17%	7 Missing and 4 partials ⚠️
plistsync/services/spotify/playlist.py	79.06%	5 Missing and 4 partials ⚠️
plistsync/services/traktor/library.py	81.57%	2 Missing and 5 partials ⚠️
plistsync/services/traktor/playlist.py	94.11%	1 Missing and 1 partial ⚠️
plistsync/services/spotify/api.py	0.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[github-actions]

Thank you for the PR! The changelog has not been updated, so here is a friendly reminder to check if you need to add an entry.