feat(terminal): Kitty only — drop Ghostty (#95)

Ghostty's OpenGL 4.3 floor broke the Acer (HD 4000 / 4.2). Dual-terminal
support (default Ghostty + install-time Kitty fallback) was more complexity
than it was worth.

- Remove ghostty.nix / nomarchy.ghostty.enable
- Kitty always installed and themed from theme-state
- Default nomarchy.terminal = kitty; SUPER+Return, doctor, calendar,
  what-changed use kitty --class=com.nomarchy.*
- Drop install-time glxinfo probe and mesa-demos on the installer
- Docs/REQUIREMENTS no longer list OpenGL 4.3 as a terminal floor

Verified: V0 flake check; option-docs; installer-safety; template HM has
kitty, no ghostty; menu/calendar emit classed kitty launches.

modules/home/kitty.nix

@@ -1,26 +1,13 @@
-# Kitty — fallback terminal when Ghostty cannot run (OpenGL < 4.3 on
-# older GPUs, e.g. Intel HD 4000). Themed from the same theme-state.json
-# as Ghostty so a machine that needs the fallback still looks like
-# Nomarchy. Enabled when nomarchy.terminal is "kitty" (installer sets
-# that after a GL probe) or when nomarchy.kitty.enable is forced on.
+# Kitty — Nomarchy's only terminal, themed from theme-state.json.
+# Colors, fonts and the full 16-color ANSI palette are baked from the
+# JSON at eval time (same contract Ghostty used to have). Always
+# installed: SUPER+Return, SUPER+E, doctor, calendar, and $TERMINAL
+# all depend on it.
 { config, lib, ... }:
 
 let
   t = config.nomarchy.theme;
   c = t.colors;
-  # Default terminal may be a bare name ("kitty") or a path; match the
-  # basename so settings.terminal = "kitty" and nomarchy.terminal =
-  # "${pkgs.kitty}/bin/kitty" both light this module.
-  terminalIsKitty =
-    let
-      term = config.nomarchy.terminal;
-      base = lib.last (lib.splitString "/" term);
-    in
-    base == "kitty" || lib.hasPrefix "kitty " term;
-
-  enabled = config.nomarchy.kitty.enable || terminalIsKitty;
-
-  # Kitty colorN = ANSI 0–15 from the theme palette.
   colorSettings = lib.listToAttrs (
     lib.imap0 (i: color: {
       name = "color${toString i}";
@@ -29,35 +16,37 @@ let
   );
 in
 {
-  config = lib.mkIf enabled {
-    programs.kitty = {
-      enable = true;
-      shellIntegration.enableBashIntegration = true;
-      shellIntegration.enableZshIntegration = true;
+  # Kitty is ALWAYS installed. `nomarchy.kitty.enable` gates only whether
+  # Nomarchy's theming/config is applied — a user can keep kitty but drop
+  # our config; they cannot remove kitty itself without breaking the
+  # desktop's load-bearing classed windows.
+  programs.kitty = {
+    enable = true;
+    shellIntegration.enableBashIntegration = true;
+    shellIntegration.enableZshIntegration = true;
 
-      font = {
-        name = t.fonts.mono;
-        size = t.fonts.size;
-      };
-
-      settings = {
-        background = c.base;
-        foreground = c.text;
-        cursor = c.accent;
-        cursor_text_color = c.base;
-        selection_background = c.overlay;
-        selection_foreground = c.text;
-        url_color = c.accent;
-        active_border_color = c.accent;
-        inactive_border_color = c.surface;
-        # Match Ghostty's padding / opacity so the two terminals feel
-        # like the same product when a machine falls back.
-        background_opacity = t.ui.terminalOpacity;
-        window_padding_width = lib.mkDefault 12;
-        confirm_os_window_close = lib.mkDefault 0;
-        enable_audio_bell = lib.mkDefault false;
-        wayland_titlebar_color = lib.mkDefault "background";
-      } // colorSettings;
+    font = lib.mkIf config.nomarchy.kitty.enable {
+      name = t.fonts.mono;
+      size = t.fonts.size;
     };
+
+    settings = lib.mkIf config.nomarchy.kitty.enable ({
+      background = c.base;
+      foreground = c.text;
+      cursor = c.accent;
+      cursor_text_color = c.base;
+      selection_background = c.overlay;
+      selection_foreground = c.text;
+      url_color = c.accent;
+      active_border_color = c.accent;
+      inactive_border_color = c.surface;
+      background_opacity = t.ui.terminalOpacity;
+      window_padding_width = lib.mkDefault 12;
+      confirm_os_window_close = lib.mkDefault 0;
+      enable_audio_bell = lib.mkDefault false;
+      wayland_titlebar_color = lib.mkDefault "background";
+      # Fresh windows for doctor/calendar --class launches (not one shared instance).
+      single_instance = lib.mkDefault false;
+    } // colorSettings);
   };
 }