~~makePlacementWorker()~~

Bake static placements on a worker, main-thread side: makeSceneWorker under its older name, typed as the bake-only PlacementWorker. Give it to makeInstanceLayer(target, { placement }), which bakes there as before; to encode models on it as well, use makeSceneWorker and the layer's worker option.

function makePlacementWorker(opts: PlacementWorkerOptions): PlacementWorker;