`waitForever()` is a public library export used by long-running embeds to
block until the host process is asked to exit. It called `interval.unref()`
on the keep-alive timer, which removes the timer from Node's active-handle
set. With no other ref'd handles, `await waitForever()` exits the process
in ~3ms with exit code 13 ("unsettled top-level await") instead of waiting.
Drop the `.unref()` so the interval actually keeps the loop alive, and
update the existing unit test (and comment) to lock in the new contract.
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
eca9645365