cancel
Request cancellation of the design point with the given 1-based pointId. If that point's coroutine is currently running (or queued) it will be cancelled; the resulting outcome carries wasCancelled = true so the commit phase fires onDesignPointCancelled instead of treating it as a failure, and skips the database write entirely.
Safe to call from any thread. Returns true if a matching active job was found and cancellation was requested; false if the point was unknown, already completed, or no simulate(...) is currently in flight.
No-op when the point has already completed — there's nothing to cancel, and the recorded outcome (success / failure) is preserved.