fix(nix): simplify protontweaks config setup

nix/home-manager.nix

@@ -2,25 +2,29 @@
 let
   cfg = config.services.protontweaks;
 
-  inherit (lib) mkIf mkEnableOption;
-in
-{
-  options.services.protontweaks = {
-    enable = mkEnableOption "protontweaks";
+  inherit (lib) mkIf mkEnableOption mkOption types;
+  inherit (types) nullOr;
 
-    gamemode = mkEnableOption "automatic gamemode initialization" // {
-      default = true;
-    };
+  protontweaksConfig = with types; submodule
+    {
+      options = {
+        gamemode = mkEnableOption "automatic gamemode initialization" // {
+          default = true;
+        };
 
-    mangohud = mkEnableOption "automatic mangohud initialization" // {
-      default = false;
+        mangohud = mkEnableOption "automatic mangohud initialization" // {
+          default = false;
+        };
+      };
     };
+in
+{
+  options.services.protontweaks.config = mkOption {
+    description = "The protontweaks config";
+    type = nullOr (protontweaksConfig);
   };
 
-  config = mkIf (cfg.enable) {
-    home.file.".config/protontweaks.json".text = builtins.toJSON ({
-      gamemode = cfg.gamemode;
-      mangohud = cfg.mangohud;
-    });
+  config = mkIf (cfg.config != null) {
+    home.file.".config/protontweaks.json".text = builtins.toJSON cfg.config;
   };
 }