- Reset _next_bound_idx in remove_unfinished() so discarded pending
  bound points can be asked again (previously they were silently
  retired and the domain corners never sampled).
- Replace the unreachable 'raise StopIteration' with a RuntimeError;
  StopIteration would surface as a confusing PEP 479 RuntimeError from
  the generator in _ask_and_tell_pending anyway.
- Drop the brittle message-matching try/except in
  _try_adding_pending_point_to_simplex; _is_known_point makes that
  path unreachable and its cleanup was incomplete.
- Scale _is_known_point tolerance with coordinate magnitude instead of
  flooring at an absolute 1e-10, which was too coarse for tiny domains.
- Simplify the regression test: derive the drifted hull vertex instead
  of magic constants, use pytest.importorskip, and remove the half that
  re-installed the old implementation to assert it fails.
- Add a regression test for the remove_unfinished bound-point reset.