feat(mirada): mirada-brain — orquestador de escritorio del compositor

Desktop agnóstico de GPUI/smithay: salidas, 9 escritorios virtuales,
registro de ventanas y foco. on_event(BodyEvent) -> Vec<BrainCommand>;
DesktopAction + mapa de teclas estilo tiling WM (Super). 17 tests.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Cargo.lock

@@ -7390,6 +7390,14 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "mirada-brain"
+version = "0.1.0"
+dependencies = [
+ "mirada-layout",
+ "mirada-protocol",
+]
+
 [[package]]
 name = "mirada-layout"
 version = "0.1.0"