feat(serpantinum): enable idle configuration

modules/hm/desktop/serpantinum.nix

@@ -1,5 +1,4 @@
 {inputs, ...}: {
-
   flake.modules.nixos.desktop = {
     imports = [
       inputs.serpantinum.nixosModules.default
@@ -62,6 +61,11 @@
           position = "top right";
           sound = true;
         };
+
+        idle = {
+          enabled = true;
+          manualInhibit = true;
+        };
       };
     };
   };