fix(slint): follow chip, playlist card size, track row hover, dedupe

- Follow button on the artist card is no longer a pill — Radius.sm
  rounded rectangle, matching the rest of the app (new ADR-008).
- PlaylistCard sized identically to AlbumCard (220x266) with the same
  220px artwork area; collage and the grid/carousel updated to match.
- Track row play overlay now appears anywhere over the row, not only
  when the pointer is directly over the cell. Slint does not propagate
  has-hover to ancestor TouchAreas, so each row OR-s its own ta with
  every nested TouchArea (play-cell, fav/dl/more) into row-hovered.
- EqualizerBars sit on a fixed 16px baseline so the animation stays
  perfectly centered while the bar heights oscillate.
- TrackPlayCell exposes out hovered so rows can OR it cleanly.
- Search dedupes a top-result artist that is also the first carousel
  entry, removing the redundant duplicate.

cc

crates/qbz-slint/ui/discover/PlaylistCarousel.slint

@@ -68,9 +68,9 @@ export component PlaylistCarousel inherits VerticalLayout {
     callback view-all-clicked();
     callback media-action(string, string, string);
 
-    property <length> card-width: 162px;
-    property <length> card-height: 210px;
-    property <length> gap: 24px;
+    property <length> card-width: 220px;
+    property <length> card-height: 266px;
+    property <length> gap: 32px;
 
     property <int> count: root.playlists.length;
     property <int> per-page: Math.max(