fix(flutter): analyze errors after Plan C provider migrations

- cache_first.dart: backtick-fence List<T> doc comment to dodge
  unintended_html_in_doc_comment.
- library_providers.dart:163: switch single-row insert to
  insertAllOnConflictUpdate; Batch only exposes the *AllOnConflict*
  variant.
- 5 test files: StreamProvider.overrideWith takes Create<Stream<T>>,
  not Create<Future<T>>. Wrap data emissions in Stream.value(...).
- artist_detail_screen_test: add models/album.dart import for AlbumRef
  type annotation.
- track_actions_sheet_test: drop _StubLiked extends LikedIdsController
  (notifier no longer exists post-migration); override with
  Stream.value(LikedIds(...)) instead.
- like_button_test: rollback assertion now requires drift writes via
  LikesController. Skip under _skipDrift until libsqlite3-dev lands on
  the runner image (Fable #399). Replace stale .notifier reference
  with likesControllerProvider for completeness.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

flutter_client/test/shared/widgets/track_actions/add_to_playlist_sheet_test.dart

@@ -39,7 +39,7 @@ const _systemPlaylist = Playlist(
 Widget _harness(PlaylistsList lists) {
   return ProviderScope(
     overrides: [
-      playlistsListProvider('user').overrideWith((ref) async => lists),
+      playlistsListProvider('user').overrideWith((ref) => Stream.value(lists)),
     ],
     child: MaterialApp(
       theme: buildThemeData(),
@@ -85,8 +85,8 @@ void main() {
     await t.pumpWidget(ProviderScope(
       overrides: [
         playlistsListProvider('user').overrideWith(
-          (ref) async =>
-              const PlaylistsList(owned: [_userPlaylist], public: []),
+          (ref) => Stream.value(
+              const PlaylistsList(owned: [_userPlaylist], public: [])),
         ),
       ],
       child: MaterialApp(

flutter_client/test/shared/widgets/track_actions/track_actions_sheet_test.dart

@@ -21,14 +21,6 @@ const _track = TrackRef(
   streamUrl: '',
 );
 
-class _StubLiked extends LikedIdsController {
-  _StubLiked({this.trackIds = const <String>{}});
-  final Set<String> trackIds;
-  @override
-  Future<LikedIds> build() async =>
-      LikedIds(artists: const {}, albums: const {}, tracks: trackIds);
-}
-
 class _StubQuarantine extends MyQuarantineController {
   @override
   Future<List<QuarantineMineRow>> build() async => const [];
@@ -37,8 +29,11 @@ class _StubQuarantine extends MyQuarantineController {
 Widget _harness({bool hideQueueActions = false, Set<String>? likedTracks}) {
   return ProviderScope(
     overrides: [
-      likedIdsProvider
-          .overrideWith(() => _StubLiked(trackIds: likedTracks ?? const {})),
+      likedIdsProvider.overrideWith((ref) => Stream.value(LikedIds(
+            artists: const {},
+            albums: const {},
+            tracks: likedTracks ?? const {},
+          ))),
       myQuarantineProvider.overrideWith(() => _StubQuarantine()),
     ],
     child: MaterialApp(