modules: add ergodox

This enables usage of ZSA tools, such as `wally` or their online
training tool for any users that are part of `plugdev`.

modules/ergodox.nix

@@ -0,0 +1,16 @@
+# ZSA keyboard udev rules
+{ config, lib, ... }:
+let
+  cfg = config.my.modules.ergodox;
+in
+{
+  options.my.modules.ergodox = with lib; {
+    enable = mkEnableOption "ZSA udev rules and user group configuration";
+  };
+
+  config = lib.mkIf cfg.enable {
+    hardware.keyboard.zsa.enable = true;
+
+    users.extraGroups = [ "plugdev" ];
+  };
+}