fix(hypr): reliable gaming workspace focus across monitors

- Add game-focus-watcher: listens on hyprland socket, auto-focuses
  gaming workspace when a game opens, closing any special workspace
  on DP-1 first via --batch to avoid async dispatch races
- Add gaming-focus script: SUPER+G now handles special workspaces on
  DP-1 regardless of focused monitor, with toggle-back behavior
- Fix steam windowrule to send all class:steam windows to special:steam,
  not just title:Steam, preventing dialogs leaking to normal workspaces
- Fix monitor 0 -> monitor DP-1 in mkGameRules and steam_app rules
  so games always launch at correct resolution on the gaming monitor
- Extract gamingMonitor variable as single source of truth

apps/ghostty/default.nix

@@ -74,7 +74,7 @@
   ];
 
   wayland.windowManager.hyprland.settings.exec-once = [
-    "[workspace special:preload silent] uwsm app -- xdg-terminal-exec"
     "[workspace 1] uwsm app -- ghostty -e bash -c 'fastfetch; exec $SHELL'" # TODO: must be xdg-terminal-exec, or default user terminal
+    "[workspace special:preload silent] uwsm app -- xdg-terminal-exec"
   ];
 }