Closes the deferred MiniPlayer follow-up from the TrackActions slice.
MiniPlayer gains a TrackActionsButton next to play/pause with
hideQueueActions=true (the playing track is the queue entry itself).
Shell architecture: ShellScaffold now takes navController + owns a
shell-scoped SnackbarHost backed by a TrackActionsViewModel
hiltViewModel() at the shell level. Snackbars triggered by the
MiniPlayer's kebab surface there; per-screen kebabs continue to
flow through each screen's own Scaffold SnackbarHost (independent
collectors so the two never compete).
All 14 ShellScaffold call sites in MinstrelNavGraph updated to pass
navController; mechanical sweep.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>