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.

README.md

@@ -19,7 +19,7 @@ partial.
 ┌──────────────────────────────────────────────────────────────────────────┐
 │  Home Manager bakes EVERYTHING into one read-only generation:            │
 │    Hyprland (colors/gaps/borders)      Waybar (palette or whole-swap)    │
-│    Ghostty (full ANSI palette)         btop (asset or generated)         │
+│    Kitty (full ANSI palette)           btop (asset or generated)         │
 │    Stylix → GTK, Qt, cursors, fonts                                      │
 └───────────────────────────────────┬──────────────────────────────────────┘
                                     ▼
@@ -56,7 +56,7 @@ Flat on purpose. Two module trees, one options file each, no hidden layers.
 │       ├── stylix.nix             #   GTK/Qt/cursors/fonts from the same JSON
 │       ├── hyprland.nix           #   all JSON-driven
 │       ├── waybar.nix
-│       ├── ghostty.nix
+│       ├── kitty.nix
 │       ├── btop.nix
 │       ├── rofi.nix               #   launcher + nomarchy-menu (calc, emoji, clip…)
 │       ├── keybinds.nix           #   single source: Hyprland binds + SUPER+? sheet
@@ -103,8 +103,8 @@ probably shouldn't exist.
 ## 2. Try it first (live ISO)
 
 **Before you install:** check **[docs/REQUIREMENTS.md](docs/REQUIREMENTS.md)**
-(UEFI x86_64, **OpenGL 4.3** for the default terminal, disk planning for the
-Nix store + BTRFS snapshots — 128 GiB is the comfortable floor).
+(UEFI x86_64, disk planning for the Nix store + BTRFS snapshots — 128 GiB is
+the comfortable floor).
 
 Boot the full desktop from a USB stick or VM without installing anything:
 
@@ -244,8 +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"` (or `"kitty"`) | Terminal for keybinds and `$TERMINAL`; installer sets `settings.terminal = "kitty"` when OpenGL < 4.3 |
-| `nomarchy.kitty.enable` | `false` | Themed Kitty (also auto-on when terminal is kitty) |
+| `nomarchy.terminal` | `"kitty"` | Terminal for keybinds and `$TERMINAL` (Kitty is the only shipped/themed emulator) |
+| `nomarchy.kitty.enable` | `true` | Nomarchy's Kitty config (palette/font/opacity from theme-state) |
 | `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 |
@@ -264,7 +264,6 @@ two tables below are split along exactly that line.
 | `nomarchy.yazi.enable` | `true` | yazi TUI file manager, themed + curated plugins |
 | `nomarchy.osd.enable` | `true` | swayosd on-screen display for volume/brightness/mute |
 | `nomarchy.shell.enable` | `true` | zsh + starship prompt + bat/eza/zoxide (zsh is the default login shell) |
-| `nomarchy.ghostty.enable` | `true` | Nomarchy's Ghostty |
 | `nomarchy.btop.enable` | `true` | btop with per-theme colors |
 | `nomarchy.stylix.enable` | `true` | GTK/Qt/cursor theming |
 | `nomarchy.fastfetch.enable` | `true` | fastfetch fronted by the themed Nomarchy logo |
@@ -376,7 +375,7 @@ source. It must be git-tracked (`nomarchy-theme-sync` runs
 
 `nomarchy-theme-sync apply <theme>` merges the preset into the JSON and runs
 `home-manager switch` (override the command with `$NOMARCHY_REBUILD`, or pass
-`--no-switch` to only write). Everything is baked: Hyprland, Waybar, Ghostty,
+`--no-switch` to only write). Everything is baked: Hyprland, Waybar, Kitty,
 btop, and — via Stylix, mapped onto base16 roles — GTK, Qt, cursors and
 fonts. No runtime patching means no partial states, and `home-manager
 generations` is also your theme history. Waybar even restyles in place: it