Service workers

Service workers are not part of core/browser/build.js and are not installed by the HyperToken Engine. Existing example PWAs contain their own worker assets, including examples/blackjack/web/sw.js and examples/cuttle/web/service-worker.js.

Treat those files as example-application behavior. A custom browser client must explicitly register and version its own service worker if it needs one, and must test cache invalidation for bundle and HTML updates. Do not infer offline CRDT sync from a service worker: local Chronicle persistence and network reconnect are separate features.