add nixos-facter to base system

nixosModules/clanCore/packages.nix

@@ -1,12 +1,21 @@
 { pkgs, ... }:
 {
-  environment.systemPackages = [
+  pkgs,
+  lib,
+  config,
+  ...
+}:
+{
+  environment.systemPackages =
+    [
       # essential debugging tools for networked services
       pkgs.dnsutils
       pkgs.tcpdump
       pkgs.curl
       pkgs.jq
       pkgs.htop
+
+    pkgs.nixos-facter # for `clan machines update-hardware-config --backend nixos-facter`
     # needed to deploy via `clan machines update` if the flake has a git input
     pkgs.gitMinimal
   ];