playArtist() previously swallowed all exceptions with a comment
about a 'future refinement' — if the tracks fetch failed or the
artist had no playable tracks, the button looked broken with no
feedback.
Now: ArtistDetailViewModel exposes a transientMessages Flow backed
by a buffered Channel. playArtist sends "Couldn't start playback:
<reason>" on Throwable and "No tracks to play for this artist."
when the result is empty. ArtistDetailScreen collects the Flow into
a Scaffold-level SnackbarHost so users see the failure inline
instead of tapping a dead button repeatedly.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen
d8459a2674