We do support this in js.Batch, but js.Build and the upcoming css.Build returns a single Resource.

This relates to my work in #14610, but I create an issue here for discoverability.

For CSS, the use case is typically loading of e.g. ttf fonts and e.g.

body {
  background-image: url("a/pixel.png");
}

I'm not prepared to overcomplicate this, so I'm going to do it the same way we handle source maps: Write the files relative to the stylesheet inside /public.

There would be no way to e.g. process these images, but ESBuild will insert a hash, so that's good.

/cc @jmooring