add templates for host specific and global overlays

hosts/desktop/default.nix

@@ -2,9 +2,19 @@
 #  Hades desktop — system configuration
 #
 
-{ lib, pkgs, pkgs-kabbone, ... }:
+{ lib, pkgs, inputs, ... }:
 
 {
+  # Example: host-specific overlays — only hades gets these packages in its pkgs.
+  # nixpkgs.overlays = [
+  #   (final: prev: {
+  #     # pull a single package from unstable (no specialArgs needed)
+  #     firefox          = inputs.nixpkgs-unstable.legacyPackages.${prev.system}.firefox;
+  #     # pull a package from pkgs-kabbone (inline import, no specialArgs needed)
+  #     corosync-qdevice = (import ../../packages { pkgs = prev; }).corosync-qdevice;
+  #   })
+  # ];
+
   imports = [
     ./hardware-configuration.nix
     ../../modules/desktop