feat: add host device type metadata

modules/hosts/polaris/default.nix

@@ -14,13 +14,8 @@ in
       pkgs,
       ...
     }:
-    let
-      host = {
-        isServer = false;
-      };
-    in
     {
-      _module.args.host = host;
+      _module.args.hostType = "desktop";
 
       imports = [
         nixosModules.desktopBase