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.

pkgs/nomarchy-install/nomarchy-install.sh

@@ -625,47 +625,6 @@ python3 "$SHARE/patch-template.py" "$FLAKE_DIR" <<PYJSON
 }
 PYJSON
 
-# Ghostty requires OpenGL 4.3 (docs/REQUIREMENTS.md). On older GPUs (Intel
-# HD 4000 / Ivy Bridge tops at 4.2) it cannot map a surface. Prefer Kitty
-# as the default terminal when we can prove the floor is missing — written
-# into theme-state.json so SUPER+Return works after first boot without a
-# hand edit. Unknown probe → leave Ghostty (do not guess on headless VMs).
-gl_ver=""
-if command -v glxinfo >/dev/null 2>&1; then
-    gl_ver=$(
-        { DISPLAY="${DISPLAY:-:0}" WAYLAND_DISPLAY="${WAYLAND_DISPLAY:-}" \
-            glxinfo -B 2>/dev/null || glxinfo -B 2>/dev/null || true; } \
-          | sed -n 's/.*OpenGL version string: \([0-9][0-9]*\.[0-9][0-9]*\).*/\1/p' \
-          | head -1
-    )
-fi
-if [[ -n "$gl_ver" ]]; then
-    gl_major=${gl_ver%%.*}
-    gl_minor=${gl_ver#*.}
-    gl_minor=${gl_minor%%.*}
-    if (( gl_major < 4 || (gl_major == 4 && gl_minor < 3) )); then
-        info "OpenGL $gl_ver < 4.3 — default terminal → kitty (Ghostty needs 4.3)"
-        python3 - "$FLAKE_DIR/theme-state.json" <<'PY'
-import json, sys
-path = sys.argv[1]
-with open(path, encoding="utf-8") as f:
-    state = json.load(f)
-settings = state.setdefault("settings", {})
-# Do not clobber an explicit user/template choice.
-if not settings.get("terminal"):
-    settings["terminal"] = "kitty"
-    settings["terminalReason"] = "opengl-below-4.3"
-with open(path, "w", encoding="utf-8") as f:
-    json.dump(state, f, indent=2)
-    f.write("\n")
-PY
-    else
-        info "OpenGL $gl_ver ≥ 4.3 — keeping Ghostty as the default terminal"
-    fi
-else
-    info "OpenGL version not probed (glxinfo unavailable or no display) — Ghostty stays default"
-fi
-
 # The flake.lock: composed offline — nomarchy is path-locked to the very
 # source the ISO carries (original stays the forge URL, so a later
 # `nix flake update` on the installed machine re-resolves normally).