install chatgpt desktop and fix default applications

modules/capabilities/desktop-defaults.nix

@@ -67,7 +67,7 @@
   };
 
   flake.modules.homeManager.workstation-apps =
-    { pkgs, ... }:
+    { lib, pkgs, ... }:
     {
       home.packages = with pkgs; [
         spotify
@@ -77,6 +77,7 @@
         pinta
         zellij
       ];
+      xdg.mimeApps.defaultApplicationPackages = lib.mkAfter [ pkgs.onlyoffice-desktopeditors ];
     };
 
   flake.modules.homeManager.xdg =