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.

pkgs/nomarchy-install/default.nix

@@ -15,6 +15,7 @@
 , pciutils         # lspci
 , usbutils         # lsusb (fingerprint-reader VID probe; sysfs is the fallback)
 , btrfs-progs      # inspect-internal map-swapfile (hibernation offset)
+, mesa-demos       # glxinfo — OpenGL probe for Ghostty floor (needs 4.3)
 , xkeyboard_config # human-readable installed layout/variant catalog
   # Baked metadata — what this installer installs and where it came from.
 , templateDir              # templates/downstream (home.nix, theme-state.json)
@@ -64,6 +65,7 @@ stdenvNoCC.mkDerivation {
       --prefix PATH : ${lib.makeBinPath [
         bash gum disko whois git python3
         util-linux gptfdisk parted cryptsetup lvm2 pciutils usbutils btrfs-progs
+        mesa-demos
       ]} \
       --set NOMARCHY_INSTALL_SHARE "$share" \
       --set NOMARCHY_XKB_RULES ${xkeyboard_config}/share/X11/xkb/rules/base.lst \

pkgs/nomarchy-install/nomarchy-install.sh

@@ -625,6 +625,47 @@ 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).