ShellScaffold already collects TrackActionsViewModel.transientMessages
into its own SnackbarHost. Per-route, the shell's hiltViewModel<
TrackActionsViewModel>() and the screen's hiltViewModel<TrackActions
ViewModel>() resolve to the same NavBackStackEntry-scoped instance,
so any kebab action fires the snackbar twice today (once in the
screen's own SnackbarHost, once in the shell's).
Strip the per-screen wiring from the four shell-wrapped screens that
had it (Library, Search, AlbumDetail, PlaylistDetail): VM param,
SnackbarHostState, LaunchedEffect, and the Scaffold's snackbarHost.
The shell now owns the snackbar exclusively.
NowPlayingScreen is intentionally left untouched -- it's outside the
shell (full-screen route), so its own snackbar wiring is the only
surface that shows the message.
bvandeusen
453f8a387b