feat: add host device type metadata

modules/hosts/orion/default.nix

@@ -9,13 +9,8 @@ in
 {
   flake.modules.nixos.orion =
     { pkgs, ... }:
-    let
-      host = {
-        isServer = true;
-      };
-    in
     {
-      _module.args.host = host;
+      _module.args.hostType = "server";
 
       imports = [
         inputs.home-manager.nixosModules.home-manager

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

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