fix(slint): widen artists carousel and make the filter apply

- The most-popular row used alignment:start, which packed the artists
  carousel to its preferred width (one card). Dropped it so the
  carousel stretches and shows as many cards as fit.
- The searchType filter only re-queried on per-type tabs (none on All,
  so it did nothing). It now re-queries albums/tracks/artists with the
  search_type and replaces all three lists, so it applies on every tab.

cc

crates/qbz-slint/ui/search/SearchResultsView.slint

@@ -431,7 +431,6 @@ export component SearchResultsView inherits Rectangle {
                 // ---- Most popular + Artists (All tab) ---------------------
                 if SearchState.tab == 0 && SearchState.most-popular-kind != "": HorizontalLayout {
                     spacing: 24px;
-                    alignment: start;
 
                     // Most-popular hero column.
                     VerticalLayout {