feat(search): add search type filters for refined results

Backend:
- Add search_type parameter to search_albums, search_tracks, search_artists
- Pass optional type filter to Qobuz API (Performer, Composer, Label, ReleaseName)

Frontend:
- Add SearchFilterType to search state management
- Add filter radio buttons in SearchView (visible when results exist)
- Remove redundant counts from tabs
- Add Clear filter button independent from Clear search
- Filters reset automatically when starting new search or clearing

Filters allow finding performers, composers, and labels that default
search misses (e.g., searching "Nicko McBrain" with Performer filter
shows Iron Maiden tracks)

src/routes/+page.svelte

@@ -512,6 +512,7 @@
     setSearchState({
       query: name,
       activeTab: 'all',
+      filterType: null,
       albumResults: null,
       trackResults: null,
       artistResults: null,