backwards: Add enable option to syncthing module

hosts/backwards/modules/default.nix

@@ -12,6 +12,7 @@ in
 
       ssh.enable = true;
       git.enable = true;
+      syncthing.enable = true;
     };
   };
 }

hosts/backwards/modules/syncthing/default.nix

@@ -1,5 +1,15 @@
-{ config, ... }:
+{ lib, config, ... }:
+let
+  enabled = config.mod.syncthing.enable;
+in
 {
+  options = {
+    mod.syncthing = {
+      enable = lib.mkEnableOption "Enable syncthing module";
+    };
+  };
+
+  config = lib.mkIf enabled {
     services.syncthing = {
       enable = true;
       openDefaultPorts = true;
@@ -85,4 +95,5 @@
         "syncthing-key".file = ../../../../secrets/backwards/syncthing-key.age;
       };
     };
+  };
 }