feat(flutter): adopt MainAppBarActions in Home + Library

HomeScreen drops its 5 ad-hoc IconButton actions in favour of the shared
widget. LibraryScreen gains an actions row it didn't have before. Both
now consistent.

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

flutter_client/lib/library/library_screen.dart

@@ -15,6 +15,7 @@ import '../models/page.dart' as wire;
 import '../models/quarantine_mine.dart';
 import '../models/track.dart';
 import '../player/player_provider.dart';
+import '../shared/widgets/main_app_bar_actions.dart';
 import '../theme/theme_extension.dart';
 import 'widgets/album_card.dart';
 import 'widgets/artist_card.dart';
@@ -90,6 +91,7 @@ class _LibraryScreenState extends ConsumerState<LibraryScreen>
         backgroundColor: fs.obsidian,
         elevation: 0,
         title: Text('Library', style: TextStyle(color: fs.parchment)),
+        actions: const [MainAppBarActions(currentRoute: '/library')],
         bottom: TabBar(
           controller: _ctrl,
           isScrollable: true,