Album/artist downloads expand to tracks with pinned parent metadata,
aggregate progress, container deletes with reference-counted album
covers, and a Music tab on the downloads screen with fully offline
album playback. Home rows include music libraries (fixes plex hub
items being filtered to video types) and audio playlists join
download/sync rules.
The aired-order rework can sweep correctly-placed Specials into "download
next N"; this toggle lets users opt out. Shown only for whole shows
(reusing FocusableSwitchListTile via an optional toggle on the shared
option-picker dialog), remembered across opens via a BoolPref
(default on = unchanged behavior). Filters Specials at the single
collect choke point (_collectPlayable), with a guard so explicitly
downloading the Specials season still queues its episodes.
edde746