feat(bluetooth): add enable option

modules/bluetooth/default.nix

@@ -1,4 +1,12 @@
+{ lib, config, ... }:
+
+let
+  cfg = config.bluetooth;
+in
 {
+  options.bluetooth.enable = lib.mkEnableOption "bluetooth";
+
+  config = lib.mkIf cfg.enable {
     hardware.bluetooth = {
       enable = true;
       powerOnBoot = true;
@@ -12,4 +20,5 @@
         };
       };
     };
+  };
 }