A search-owned track row modelled on the album-page track row, but the
leading slot is a cover thumbnail (search tracks span many albums).
show-artwork keeps the slot configurable for a future shared component.
Compiled once SearchResultsView imports it (next task).
cc
SearchResultsView renders the four SearchState categories; mounted in
AppShell on ContentView.search. Phase 1 is now functional end to end:
header input -> debounced search -> QbzCore::search_all -> results.
Phase 2 builds this into the tabbed dashboard.
cc
vicrodh