feat: add host device type metadata

modules/hosts/zenith/default.nix

@@ -10,13 +10,8 @@ in
 {
   flake.modules.nixos.zenith =
     { ... }:
-    let
-      host = {
-        isServer = false;
-      };
-    in
     {
-      _module.args.host = host;
+      _module.args.hostType = "laptop";
 
       imports = [
         nixosModules.desktopBase