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/jellyfin/session_media.dart

@@ -332,13 +332,13 @@ Duration nextPromptStart(JellyfinItem? item, Duration runtime, {Duration? ending
 
 /// Who performs the auto-advance swap, so several counting clients do not
 /// swap twice: the lowest member id among members that play the item with
-/// their own account (`jf[serverId] == true`, not stale). Only what every
+/// their own account (`jf[serverId] == true`, not stale, not out). Only what every
 /// client sees in `state` decides (who put the item up is not in it: a
 /// late joiner never saw that swap), so all clients agree.
 String? autoAdvanceSwapper(List<MemberView> members, String serverId) {
   final eligible = [
     for (final m in members)
-      if (!m.stale && m.jf[serverId] == true) m
+      if (!m.stale && !m.out && m.jf[serverId] == true) m
   ];
   if (eligible.isEmpty) return null;
   eligible.sort((a, b) => compareMemberIds(a.id, b.id));