chore(nix): refactor Headscale service configuration

- Reorganized `settings` block to simplify and correct nesting.
- Updated function arguments to include variadic parameters for extensibility.

systems/x86_64-linux/mx/headscale.nix

@@ -1,4 +1,4 @@
-{ config }:
+{ config, ... }:
 let
   domain = "headscale.hoyer.xyz";
 in
@@ -8,12 +8,11 @@ in
       enable = true;
       address = "0.0.0.0";
       port = 8080;
+      settings = {
         server_url = "https://${domain}";
         dns = {
           baseDomain = "hoyer.tail";
         };
-      settings = {
-        logtail.enabled = false;
       };
     };