Review follow-up (Sara): j/k wrap-around and fresh-entry had no direct
coverage — the logic lived inline in the page where the action spec only
mocks the callbacks. Extracted to a pure stepRegion() with 9 unit tests
(empty list, forward/back, both wraps, fresh-entry null + unknown id,
length-1). Also replaces the inline nested ternary Felix flagged.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
