Add a Bootstrap-style `sm` flag to the shared toolbar primitives
(QbzSelect, ExpandableSearch, ToggleButton) — default stays the standard
size (Settings keeps it), and the favorites toolbar opts in (genre /
group / sort / search / grid-list now ~30px). FavGenreButton + the
favorites grid/list ViewToggle shrink to match. Also vertically center
the MultiSelectBar action buttons (only the count was centered before).
cc
Extract PlaylistView's inline bulk action bar into a shared
MultiSelectBar primitive driven by a [BulkAction] model (id / label /
danger / needs-selection) emitting action(id). PlaylistView now declares
its two actions (Select all, Remove) as data; the Favorites tracks tab
will reuse the same bar with its larger action set instead of copying
it. Same visual (count label + bordered/hover buttons, ADR-008).
cc
vicrodh