fix(flutter): drop redundant const in nested const contexts

Making the outer FabledSwordTheme(...) and HomeData(...) constructors
const made every inner const redundant — Dart's analyzer fires
unnecessary_const for each. Strip the inner consts so the outer
context owns the const inference.

flutter_client/test/library/home_screen_test.dart

@@ -12,15 +12,15 @@ import 'package:minstrel/theme/theme_data.dart';
 void main() {
   testWidgets('home renders sections with rows', (tester) async {
     const fixture = HomeData(
-      recentlyAddedAlbums: const [
+      recentlyAddedAlbums: [
         AlbumRef(id: 'a', title: 'Geogaddi', artistId: 'x', artistName: 'BoC'),
       ],
-      rediscoverAlbums: const [],
-      rediscoverArtists: const [
+      rediscoverAlbums: [],
+      rediscoverArtists: [
         ArtistRef(id: 'r', name: 'Aphex Twin'),
       ],
-      mostPlayedTracks: const [],
-      lastPlayedArtists: const [],
+      mostPlayedTracks: [],
+      lastPlayedArtists: [],
     );
     await tester.pumpWidget(ProviderScope(
       overrides: [