also refactor nixos modules

modules/nixos/desktop/gamescope.nix

@@ -0,0 +1,35 @@
+{
+  lib,
+  config,
+  ...
+}: let
+  inherit (lib) mkIf mkEnableOption mkForce;
+
+  cfg = config.sneeuwvlok.desktop.gamescope;
+in {
+  options.sneeuwvlok.desktop.gamescope = {
+    enable =
+      mkEnableOption "Enable Steamdeck ui"
+      // {
+        default = config.sneeuwvlok.desktop.use == "gamescope";
+      };
+  };
+
+  config = mkIf cfg.enable {
+    sneeuwvlok.desktop.plasma.enable = true;
+
+    services.displayManager.sddm.enable = mkForce false;
+    services.displayManager.gdm.enable = mkForce false;
+
+    jovian = {
+      steam = {
+        enable = true;
+        autoStart = true;
+        user = "chris";
+        updater.splash = "steamos";
+        desktopSession = "plasma";
+      };
+      steamos.useSteamOSConfig = true;
+    };
+  };
+}