1.3.6 never committed its shadow DOM on StrictMode's remount, so every diff
rendered blank in dev regardless of the worker pool. 1.4 fixes that and the
worker init hang (upstream #1076), so highlighting runs off-thread again.
Ports to the 1.4 API: createEditor takes (type, options, editStateKey) and
EditorOptions.onChange receives a change event. Stubs the "?worker" import for
Vitest, which has no equivalent of Vite's worker transform.