Protocol 11: sit out replaces kicking; nudge

Anyone can sit anyone out (host included); only you bring yourself back.
Out members stay in chat and the party, never block or count, and load no
media; a card with the live position and Join back (Space) replaces the
video. The mini player's x sits you out; optionally idle does too. Nudge:
the server forwards it to the target only (3/s, 20/min per sender); the
target hears the nudge sound, gets a toast and a taskbar attention
request. Kick, its messages, errors and dialog are gone.

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

apps/desktop/test/player_settings_test.dart

@@ -296,10 +296,10 @@ void main() {
           findsOneWidget);
       expect(find.descendant(of: find.byKey(const ValueKey('member-m2')), matching: find.text('host')),
           findsNothing);
-      // The host cannot be kicked: no Kick in its menu.
+      // The host can be sat out like anyone.
       await tester.tap(find.descendant(of: find.byKey(const ValueKey('member-m1')), matching: find.byTooltip('More')));
       await tester.pumpAndSettle();
-      expect(find.text('Kick'), findsNothing);
+      expect(find.text('Sit out'), findsOneWidget);
     });
 
     testWidgets('hosting: Copy invite address lists this machine\'s addresses', (tester) async {