chore: don't install snapcraft or LXD on NixOS

If I need to build snaps, I'll use Grozbok my Lima VM.

nixos/_mixins/features/snapcraft/default.nix

@@ -10,12 +10,16 @@ let
   installFor = [ "martin" ];
 in
 lib.mkIf (lib.elem "${username}" installFor && isWorkstation) {
-  # Install snapcraft and enable snapd (for running snaps) and lxd (for building snaps)
-  environment.systemPackages = with pkgs; [ snapcraft ];
   services.snap.enable = true;
+
+  # I've stopped using snapcraft and lxd on NixOS
+  # because I now use an Ubuntu guest for building snaps.
+  # Install snapcraft and enable snapd (for running snaps) and lxd (for building snaps)
+  #environment.systemPackages = with pkgs; [ snapcraft ];
+
   # lxd in Nixpkgs errorneously disables unified cgroup hierarchy.
   # LXD has had support for cgroups v2 since since 2020.
-  systemd.enableUnifiedCgroupHierarchy = lib.mkForce true;
-  virtualisation.lxd.enable = true;
-  users.users.${username}.extraGroups = lib.optional config.virtualisation.lxd.enable "lxd";
+  #systemd.enableUnifiedCgroupHierarchy = lib.mkForce true;
+  #virtualisation.lxd.enable = true;
+  #users.users.${username}.extraGroups = lib.optional config.virtualisation.lxd.enable "lxd";
 }