fix(jellyfin): scope global search to visible libraries

Jellyfin search rows do not expose their owning collection, so hidden libraries cannot be filtered after the response. Scope searches to visible libraries, stamp the returned rows, reuse the latest loaded views, propagate cancellation, and fail closed when views cannot be loaded.

Keep full candidate budgets and split music libraries into parallel album, audio, and artist requests. Album requests disable UserData and use the existing album field set to avoid recursive per-album work from #1552; audio requests retain cheap leaf play state.

close #1770

test/screens/search_screen_test.dart

@@ -561,7 +561,12 @@ class _FakeMediaServerClient implements MediaServerClient {
   ServerCapabilities get capabilities => ServerCapabilities.plex;
 
   @override
-  Future<List<MediaItem>> searchItems(String query, {int limit = 100, AbortController? abort}) async {
+  Future<List<MediaItem>> searchItems(
+    String query, {
+    int limit = 100,
+    AbortController? abort,
+    Set<String> excludedLibraryIds = const {},
+  }) async {
     queries.add(query);
     lastSearchAbort = abort;
     abort?.throwIfAborted();