modules: move nh from core/nix to programs

This is a user program, it cannot be in core.

modules/core/nix.nix

@@ -3,9 +3,7 @@
   pkgs,
   config,
   ...
-}: let
-  inherit (config.local.systemVars) username;
-in {
+}: {
   nix = {
     package = pkgs.lix;
     settings = {
@@ -21,14 +19,6 @@ in {
     nixPath = ["nixpkgs=${inputs.nixpkgs}"];
   };
 
-  programs.nh = {
-    enable = true;
-    clean = {
-      enable = true;
-      extraArgs = "--keep-since 30d --keep 3";
-    };
-  };
-
   nixpkgs = {
     config = {
       allowUnfree = true;
@@ -40,6 +30,4 @@ in {
       segger-jlink.acceptLicense = true;
     };
   };
-
-  hjem.users.${username}.environment.sessionVariables.FLAKE = "${config.hjem.users.${username}.directory}/.dotfiles";
 }

modules/programs/default.nix

@@ -11,6 +11,7 @@
     ./firefox.nix
     ./games.nix
     ./misc.nix
+    ./nh.nix
     ./thunar.nix
     ./waybar.nix
     ./wlogout.nix

modules/programs/nh.nix

@@ -0,0 +1,21 @@
+{
+  lib,
+  config,
+  ...
+}: let
+  inherit (lib.modules) mkIf;
+  inherit (config.local.profiles) desktop;
+  inherit (config.local.systemVars) username;
+in {
+  config = mkIf desktop.enable {
+    programs.nh = {
+      enable = true;
+      clean = {
+        enable = true;
+        extraArgs = "--keep-since 30d --keep 3";
+      };
+    };
+
+    hjem.users.${username}.environment.sessionVariables.FLAKE = "${config.hjem.users.${username}.directory}/.dotfiles";
+  };
+}