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/state/settings.dart

@@ -25,6 +25,7 @@ const _keySoundsOff = 'soundsOff';
 const _keySoundPreset = 'soundPreset';
 const _keySoundPresetFor = 'soundPresetFor';
 const _keyUnreadyOnSwap = 'unreadyOnSwap';
+const _keyIdleSitsOut = 'idleSitsOut';
 
 enum HwdecMode { auto, off, custom }
 
@@ -39,6 +40,8 @@ class AppSettings {
   /// Session: send ready=false when the video changes (a swap keeps the
   /// server's ready flags).
   final unreadyOnSwap = signal(false);
+  /// Session: the idle auto-unready sits this member out instead.
+  final idleSitsOut = signal(false);
   /// Player design: the uosc controls (`controls/uosc/`) instead of the
   /// standard ones (media_kit's with our bars). Applies live.
   final mpvControls = signal(false);
@@ -95,6 +98,8 @@ class AppSettings {
       if (advance is bool) autoAdvance.value = advance;
       final unready = box.get(_keyUnreadyOnSwap);
       if (unready is bool) unreadyOnSwap.value = unready;
+      final idleOut = box.get(_keyIdleSitsOut);
+      if (idleOut is bool) idleSitsOut.value = idleOut;
       final mpv = box.get(_keyMpvControls);
       if (mpv is bool) mpvControls.value = mpv;
       final hideRe = box.get(_keyHideReReleases);
@@ -156,6 +161,11 @@ class AppSettings {
     _put(_keyUnreadyOnSwap, on);
   }
 
+  void setIdleSitsOut(bool on) {
+    idleSitsOut.value = on;
+    _put(_keyIdleSitsOut, on);
+  }
+
   void setMpvControls(bool on) {
     mpvControls.value = on;
     _put(_keyMpvControls, on);