Turbopack: lazier manifests, part deux (#84191)
Lazily compute the contents of the client reference and the font manifests, this moves the computation to `emit` (= writing out all chunks in parallel) as opposed to `Endpoint::output` (= where we are determining the list of chunks to emit).
<img width="1891" height="910" alt="Bildschirmfoto 2025-09-24 um 18 30 13" src="https://github.com/user-attachments/assets/3d3dbd83-4125-4bb5-bb90-e38c536cc44e" />
