cook-cli: build js during preBuild

Otherwise editor.bundle.js is not included in the package and the
web editor does not load in the cook-cli webserver.

pkgs/by-name/co/cook-cli/package.nix

@@ -44,6 +44,7 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   preBuild = ''
     npm run build-css
+    npm run build-js
   '';
 
   meta = {