fix: update artifacts.nix to use fleet.modules

- Use fleet.modules instead of trying to access mkFleet output directly
- Fix netboot artifact generation to correctly access module list
- Ensure artifacts can access both nixosConfigurations and modules from fleet

installer/modules.nix

@@ -13,12 +13,15 @@
 #   inputs.athenix.nixosModules.sw
 
 { inputs }:
-# Automatically import all variant modules from variants/ directory
-# This returns an attribute set like: { nix-desktop = ...; nix-laptop = ...; nix-lxc = ...; sw = ...; }
-(import ../variants { inherit inputs; })
-// {
+# Expose hardware type modules from hw/ directory
+# This returns an attribute set like: { nix-desktop = ...; nix-laptop = ...; nix-lxc = ...; }
+let
+  hostTypes = import ../hw { inherit inputs; };
+in
+{
   # Software configuration module - main module with all athenix.sw options
   # Use athenix.sw.type to select profile: "desktop", "tablet-kiosk", "headless", "stateless-kiosk"
+  hw = hostTypes;
   sw =
     {
       inputs,