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/lib/src/shell/toasts.dart

@@ -34,11 +34,13 @@ ShellToast shellToastFor(ToastItem t, AvatarInfo Function(String name) avatar) {
       ? Icons.login
       : rest.startsWith('left')
           ? Icons.logout
-          : rest.startsWith('kicked')
-              ? Icons.gavel
-              : rest.startsWith('changed')
-                  ? Icons.swap_horiz
-                  : Icons.info_outline;
+          : rest.startsWith('sat you out')
+              ? Icons.bedtime
+              : rest.startsWith('nudged')
+                  ? Icons.notifications_active_outlined
+                  : rest.startsWith('changed')
+                      ? Icons.swap_horiz
+                      : Icons.info_outline;
   return ShellToast(id: t.id, who: avatar(n), text: rest, icon: icon);
 }