Sounds: Japanese-house sound set in the app, layout demo removed

Eleven sounds for events that carry news (ready, unready, everyone ready,
join, leave, kick, new video, others' chat, idle warning, connection
lost/back); none for what the video already says. New voices: koto
(Karplus-Strong, bendable), furin chime, rin bowl, bamboo, hyoshigi,
shoji slide, in the Yo scale on D. Played by SynthSfx at the Settings
volume with per-sound switches and previews. The debug layout mock is
gone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/test/coord_presence_test.dart

@@ -7,6 +7,7 @@ import 'package:sync_relay_core/core.dart';
 import 'package:sync_relay_server/server.dart';
 import 'package:hive_ce/hive.dart';
 import 'package:watch_together/src/session/session_coordinator.dart';
+import 'package:watch_together/src/sfx/sfx.dart';
 import 'package:watch_together/src/state/session_state.dart';
 import 'package:watch_together/src/sync/sync_client.dart';
 
@@ -214,7 +215,8 @@ void main() {
       MediaKit.ensureInitialized();
       final server = SyncServer(const AppConfig(port: 0, secret: 'toast', name: 'toast'));
       await server.start();
-      final coord = SessionCoordinator();
+      final sounds = _RecordingSfx();
+      final coord = SessionCoordinator(sfx: sounds);
       final friend = SyncClient();
       try {
         await coord.connect(ConnectParams(
@@ -227,6 +229,12 @@ void main() {
         final toasts = coord.toasts.peek();
         expect(toasts.firstWhere((t) => t.text == 'Bob Jr joined').actor, 'Bob Jr');
         expect(toasts.firstWhere((t) => t.text == 'Bob Jr: hi there').actor, 'Bob Jr');
+        // Others' chat makes a sound, your own does not.
+        expect(sounds.kinds.where((k) => k == SfxKind.chat), hasLength(1));
+        coord.sendChat('mine');
+        await _poll(() => coord.toasts.peek().any((t) => t.text == 'Bob: mine'), 'own chat');
+        expect(sounds.kinds.where((k) => k == SfxKind.chat), hasLength(1));
+        expect(sounds.kinds, contains(SfxKind.join));
       } finally {
         await friend.dispose();
         await coord.dispose();
@@ -235,3 +243,9 @@ void main() {
     },
   );
 }
+
+class _RecordingSfx implements SfxService {
+  final kinds = <SfxKind>[];
+  @override
+  Future<void> play(SfxCue cue) async => kinds.add(cue.kind);
+}