feat(jellyfin): favorites library filter + heart favorite in the rate sheet

close #1485

test/services/jellyfin_client_urls_test.dart

@@ -1598,11 +1598,22 @@ void main() {
       expect(captured!.path, '/Items/Filters');
       expect(captured!.queryParameters['ParentId'], 'lib-1');
       expect(captured!.queryParameters['userId'], 'user-1');
-      expect(result.filters.map((filter) => filter.filter), ['unwatched', 'genre', 'year', 'contentRating', 'tag']);
+      expect(result.filters.map((filter) => filter.filter), [
+        'unwatched',
+        'favorite',
+        'genre',
+        'year',
+        'contentRating',
+        'tag',
+      ]);
       expect(result.filters.first.filterType, 'boolean');
       expect(result.filters.first.key, 'jellyfin:unwatched');
       expect(result.filters.first.title, 'Unwatched');
+      expect(result.filters[1].filterType, 'boolean');
+      expect(result.filters[1].key, 'jellyfin:favorite');
+      expect(result.filters[1].title, 'Favorites');
       expect(result.cachedValues.containsKey('unwatched'), isFalse);
+      expect(result.cachedValues.containsKey('favorite'), isFalse);
       expect(result.cachedValues['genre']!.map((value) => value.key), ['Action', 'Drama']);
       expect(result.cachedValues['year']!.map((value) => value.key), ['2024', '1999']);
     });

test/services/jellyfin_mappers_test.dart

@@ -100,6 +100,32 @@ void main() {
       expect(item.isWatched, isFalse);
     });
 
+    test('maps UserData.IsFavorite and ignores the legacy Likes flag', () {
+      final json = {
+        'Id': 'fav-1',
+        'Name': 'Favorited Movie',
+        'Type': 'Movie',
+        'UserData': {'IsFavorite': true, 'Likes': true},
+      };
+
+      final item = JellyfinMappers.mediaItem(json, serverId: ServerId(_serverId), absolutizer: null)!;
+
+      expect(item.isFavorite, isTrue);
+      // Likes used to map to userRating 10.0/0.0; the rate sheet now uses
+      // IsFavorite for Jellyfin, so Likes must no longer surface anywhere.
+      expect(item.userRating, isNull);
+    });
+
+    test('missing UserData leaves isFavorite null', () {
+      final item = JellyfinMappers.mediaItem(
+        {'Id': 'no-userdata', 'Name': 'No UserData', 'Type': 'Movie'},
+        serverId: ServerId(_serverId),
+        absolutizer: null,
+      )!;
+
+      expect(item.isFavorite, isNull);
+    });
+
     test('maps generic Jellyfin video types to playable clips', () {
       final video = JellyfinMappers.mediaItem(
         {'Id': 'home-video', 'Name': 'Home Video', 'Type': 'Video'},

test/services/library_query_translator_test.dart

@@ -57,6 +57,10 @@ void main() {
       expect(params['unwatched'], '1');
     });
 
+    test('favoritesOnly is ignored (Plex has no favorites)', () {
+      expect(translator.toQueryParameters(const LibraryQuery(favoritesOnly: true)), isEmpty);
+    });
+
     test('arbitrary filter clauses pass through verbatim', () {
       final params = translator.toQueryParameters(
         const LibraryQuery(
@@ -210,6 +214,16 @@ void main() {
       expect(params['Filters'], 'IsUnplayed');
     });
 
+    test('favoritesOnly sets Filters=IsFavorite', () {
+      final params = translator.toQueryParameters(const LibraryQuery(favoritesOnly: true));
+      expect(params['Filters'], 'IsFavorite');
+    });
+
+    test('unwatched + favorites combine into a comma-separated Filters list', () {
+      final params = translator.toQueryParameters(const LibraryQuery(includeWatched: false, favoritesOnly: true));
+      expect(params['Filters'], 'IsUnplayed,IsFavorite');
+    });
+
     test('search puts text in SearchTerm', () {
       final params = translator.toQueryParameters(const LibraryQuery(search: 'matrix'));
       expect(params['SearchTerm'], 'matrix');
@@ -298,6 +312,14 @@ void main() {
       expect(roundTrip(input)['director'], '12345');
     });
 
+    test('favorite=1 maps to favoritesOnly, not a generic filter entry', () {
+      // Jellyfin-only key; the Plex translator deliberately drops it, so it
+      // must not leak into the verbatim-pass-through filters bucket either.
+      final query = libraryQueryFromPlexMap(map: {'favorite': '1'});
+      expect(query.favoritesOnly, isTrue);
+      expect(query.filters, isEmpty);
+    });
+
     test('libraryKind argument overrides any type entry in the map', () {
       // The browse tab always passes the library's actual kind; map's `type`
       // is dropped if the explicit arg is present.