fix(desktop): correct dwindle keybinds and speed up the terminal

Two issues surfaced on the live neogaia session. Hyprland rejected two names
at load: the split toggle is a dwindle layout message reached through
layoutmsg, not a top-level dispatcher, and dwindle:pseudotile no longer exists
in this version. Bind Super+T via layoutmsg and drop the pseudotile option.

Ghostty also cold-started GTK on every launch. Configure it through
home-manager with gtk-single-instance so windows after the first open in the
existing process. Record the dispatcher/option version-drift trap in CLAUDE.md.

CLAUDE.md

@@ -102,3 +102,7 @@ The domain model (Host, Module, Skeleton, Auto-loader, Enable convention, overla
   The Lua backend mangles `$mod`-style variables and INI `bind=` strings into invalid Lua (`hl.$mod("SUPER")`), and does not fail the build, since the config is only text.
   Set `configType = "hyprlang"` to get the native `hyprland.conf` whose variable and bind syntax the usual settings are written in.
   Render the file to check which format is in effect: `nix build --print-out-paths .#nixosConfigurations.<host>.config.home-manager.users.<user>.xdg.configFile.\"hypr/hyprland.conf\".source` (only the enabled `configType`'s key exists).
+- An invalid Hyprland dispatcher or config-option name never fails the nix build, since `hyprland.conf` is only text, so it surfaces only when the compositor loads the file at login.
+  The build/render check is therefore blind to it, and the real test is a running session (or reading `~/.config/hypr/hyprland.conf` against the running package's own names).
+  Two that bit on 0.55.4: the dwindle split actions `togglesplit`, `swapsplit`, and `pseudo` are layout messages reached through the `layoutmsg` dispatcher (`bind = $mod, T, layoutmsg, togglesplit`), not top-level dispatchers, and the old `dwindle:pseudotile` option is gone.
+  Confirm names against the pinned package rather than the wiki, whose "latest" drifts from it.

modules/desktop/hyprland/hyprland.nix

@@ -94,7 +94,6 @@ in
         };
 
         dwindle = {
-          pseudotile = true;
           preserve_split = true;
         };
 
@@ -121,7 +120,8 @@ in
 
           "$mod, Space, togglefloating,"
           "$mod, F, fullscreen,"
-          "$mod, T, togglesplit,"
+          # togglesplit is a dwindle layout message, reached through layoutmsg.
+          "$mod, T, layoutmsg, togglesplit"
           "$mod SHIFT, Q, killactive,"
           "$mod CTRL, Q, forcekillactive,"
         ]

modules/desktop/terminal.nix

@@ -1,7 +1,6 @@
 {
   config,
   lib,
-  pkgs,
   ...
 }:
 # Ghostty as the desktop terminal.
@@ -13,6 +12,12 @@ in
   options.modules.desktop.terminal.enable = lib.mkEnableOption "Ghostty as the desktop terminal";
 
   config = lib.mkIf cfg.enable {
-    home-manager.users.${user}.home.packages = [ pkgs.ghostty ];
+    home-manager.users.${user}.programs.ghostty = {
+      enable = true;
+
+      # Reuse a single process, so each window after the first opens instantly
+      # instead of paying a fresh GTK startup.
+      settings.gtk-single-instance = true;
+    };
   };
 }