onBlur scheduled `window.setTimeout(closeTrigger, 80)` and never cleared it, so an
editor unmounted inside that window still ran closeTrigger() → setState after
teardown. In CI vitest surfaced it as an unhandled "ReferenceError: window is not
defined" originating in paste-url-is-text.test.tsx, failing check:test:ui with all
8201 tests green. The timer now lives in a ref, is replaced on re-blur and cleared
on unmount.
597310857b