Modules compiled to bytecode ahead of time. They are registered in the
worker's context before the first evaluate, so imports of their names
resolve locally: no moduleHandler round trip, no parked worker, and no
per-module parse cost at runtime.
Module sources the worker resolves on its own, as a fallback for graphs
that are known but not precompiled. Cheaper than moduleHandler (no round
trip) but still parses on every load; bundle is the faster option.