- Library screen now has a TabBar (Alle / Künstler / Alben) inside a
DefaultTabController; scan/permission/error banners stay above the
TabBarView so they remain visible regardless of the active sub-tab
- New lib/library/song_grouping.dart: pure, unit-tested functions
groupByArtist/groupByAlbum (null artist/album -> "Unbekannt" /
"Unbekanntes Album", alphabetically sorted) plus albumArtistLabel
("Verschiedene Interpreten" when an album mixes artists)
- New lib/library/artist_list.dart + album_list.dart: StreamBuilder on
MeloDb.watchSongs(), grouped client-side, tapping a row pushes a
SongList screen for that artist/album; album rows show a CoverImage
thumbnail from the first song's coverPath
- Existing "Alle" tab content (recently-added strip, full song list,
empty state) preserved unchanged, moved into _AllSongsTab
Genre browsing is intentionally out of scope: the Songs table has no
genre column and neither scanner extracts genre metadata — needs a
schema migration + scanner work in a future task.
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
