fix(scripts): add python3 so the XPS haptic-touchpad service runs

Pillar 9 VM script sweep: nomarchy-haptic-touchpad failed with
"env: 'python3': No such file or directory". It's a python3 script
(#!/usr/bin/env python3) wired as systemd.services.nomarchy-haptic-touchpad
in core/system/hardware.nix (Dell XPS haptic feedback), run from the
nomarchy-system-scripts wrapper — but python3 wasn't in systemScriptDeps,
so the wrapper's PATH lacked it and the service died on every XPS. Add
python3 (stdlib-only script, plain pkgs.python3 suffices). Verified the
rebuilt wrapper resolves python3 and the script runs to its clean
"no device found" exit.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/system/scripts-derivation.nix

@@ -33,6 +33,7 @@ let
     fwupd
     hyprland
     swayosd
+    python3   # nomarchy-haptic-touchpad is a python3 script (Dell XPS service)
   ];
 in
 pkgs.stdenv.mkDerivation {