What problem does this feature solve?

Today, in order to use a @rolldown/browser the consumer has to have a crossOriginIsolated environment. Any chance we could get an official single threaded build that trades-off SharedArrayBuffer shared data for more flexible CORs environments?

What does the proposed API look like?

import { rolldown } from '@rolldown/browser/single-threaded';

Can be imported into a non crossOriginIsolated environment.