add nightlight

modules/graphical/nightlight.nix

@@ -0,0 +1,13 @@
+{ config, lib, pkgs, ... }:
+let cfg = config.custom.graphical.nightlight;
+in {
+  options.custom.graphical.nightlight = {
+    enable = lib.mkEnableOption "Enables nightlight";
+  };
+
+  config = lib.mkIf cfg.enable {
+    location.latitude = 48.2082;
+    location.longitude = 16.3738;
+    services.redshift.enable = true;
+  };
+}