added helvum to packages installed

modules/sound/pipewire.nix

@@ -1,6 +1,11 @@
-{...}: {
+# TODO: refactor into module
+{ pkgs, ...}: {
   services.pipewire = {
     enable = true;
     pulse.enable = true;
   };
+
+  environment.systemPackages = with pkgs; [
+    helvum
+  ];
 }