Identify bulk-added episodes already in playlists

[yaelirub]

When adding multiple episodes to a playlist, pre-select playlists that already contain all of the selected episodes.

Made-with: Claude Code

Fixes PCIOS-546

To test

1. Add multiple episodes to a manual playlist
2. Go back to the podcast's episode list
3. Enter multi-select mode and select those same episodes
4. Tap the overflow menu and select "Add to Playlist"
   Expected: The playlist containing all episodes should have its checkbox pre-selected

Checklist

• I have considered if this change warrants user-facing release notes and have added them to CHANGELOG.md if necessary.
• I have considered adding unit tests for my changes.
• I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 8.6 ❄️. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

Generated by 🚫 Danger

[bjtitus]

This worked well for me in testing. Performance could be improved by iterating each episode and fetching playlists IDs, then using Set intersection but in practice I didn't notice it on any device I tried.

It was about a 6x speed improvement:
improvement.patch

This could be fixed up with some of our other performance improvements.

[bjtitus]

This could be sped up by iterating over and storing the playlist UUIDs in a Set and intersecting the sets. The more playlists you have the more this matters and in my testing it took quite a few (many dozens + hundreds of episodes) to notice any difference. We could fix this up later or now

Suggested change

	// For bulk episodes, find playlists that contain ALL selected episodes
	var playlistsContainingAllEpisodes: Set<String> = []
	for playlist in manualPlaylists {
	let allEpisodesInPlaylist = episodes.allSatisfy { episode in
	dataManager.manualPlaylistUUIDs(for: episode.uuid).contains(playlist.uuid)
	}
	if allEpisodesInPlaylist {
	playlistsContainingAllEpisodes.insert(playlist.uuid)
	}
	}
	initialSelectedPlaylists = playlistsContainingAllEpisodes
	// For bulk episodes, find playlists that contain ALL selected episodes
	let playlistSets = episodes.map { episode in
	Set(dataManager.manualPlaylistUUIDs(for: episode.uuid))
	}
	initialSelectedPlaylists = playlistSets.dropFirst().reduce(playlistSets.first ?? []) { accumulated, uuids in
	accumulated.intersection(uuids)
	}

[yaelirub]

Great suggestion. Lets do this for next release. Can you please create a ticket for it?

[SergioEstevao]

I created an implementation on the find playlists containing episode using a direct SQL query here: #4026

I believe that approach could be more efficient when there is a lot of playlist and episodes to check.