[development] Fix humanlayer plugins

Removes model specification to better support Claude Code Pro plan.
Because of this, I also re-removed this role from home-darwin-work as we
can take advantage of more powerful models in that context. We will just
need to install the plugins external from nix. Eventually I can turn
this into a config option of course.

Also made sure we are installing the agents from the plugin in addition
to the commands.

home/home-darwin-work.nix

@@ -222,7 +222,6 @@ in
 
   home.roles = {
     base.enable = true;
-    development.enable = true;
   };
 
   imports = [