remove desktop environment from server; consolidate much-needed caps:esc switch to common users file

nix/system/common/users.nix

@@ -9,6 +9,10 @@
     ];
   };
 
+  # run the following command to swap escape and caps-lock keys, like a
+  # civilized person:
+  services.xserver.xkbOptions = "caps:swapescape";
+
   users.extraUsers.haak = {
     shell = pkgs.zsh;
   };