feat(terminal): themed Kitty when OpenGL < 4.3 (#95)

Ghostty needs OpenGL 4.3; older GPUs (Intel HD 4000) top out at 4.2.
Installer probes glxinfo and writes settings.terminal=kitty into
theme-state when below the floor. modules/home/kitty.nix enables Kitty
with the same palette, mono font, and opacity as Ghostty so the fallback
still looks like Nomarchy.

Default machines stay Ghostty-only (no kitty in the HM closure). Doctor
and calendar still invoke Ghostty by class — V3 on Acer for SUPER+Return.

Verified: V0 flake check; installer-safety; HM with terminal=kitty builds
themed kitty.conf + TERMINAL=kitty; default template has no kitty bin.

README.md

@@ -244,7 +244,8 @@ two tables below are split along exactly that line.
 | Option | Default | Purpose |
 |---|---|---|
 | `nomarchy.stateFile` | — (required) | Path to your theme-state.json |
-| `nomarchy.terminal` | `"ghostty"` | Terminal for keybinds and `$TERMINAL` |
+| `nomarchy.terminal` | `"ghostty"` (or `"kitty"`) | Terminal for keybinds and `$TERMINAL`; installer sets `settings.terminal = "kitty"` when OpenGL < 4.3 |
+| `nomarchy.kitty.enable` | `false` | Themed Kitty (also auto-on when terminal is kitty) |
 | `nomarchy.keyboard.layout` | `"us"` | XKB layout for the Hyprland session (installer writes the matching `services.xserver.xkb` in system.nix; the console + LUKS prompt follow via the distro default) |
 | `nomarchy.keyboard.variant` | `""` | XKB variant for the session |
 | `nomarchy.keyboard.devices` | `{}` | Per-device layout overrides (Hyprland `device` blocks keyed by `hyprctl devices` name) — e.g. an external keyboard with its own layout/variant |