The manifest is an artifact produced by the browser compilation, but it can be shared _before_ the browser compilation writes its results to disk.

I _could_ refactor to have "browser compilation phase 1", then assets manifest, and then "browser compilation phase 2", but that's not how I model it in my head. Plus it would mean a diverging interface for `compileBrowser` and `compileServer` which doesn't fit my mental model either.

So prefer to use channels instead.