Per WAI-ARIA, aria-selected must be on the same element carrying role="tab".
The previous impl placed it on an inner <span> via the render-prop, making it
invisible to assistive technology. Move both role="tab" and aria-selected to
the NavLink, compute currentKind once from useParams, drop the render-prop.
Add a Vitest assertion that the selected tab has aria-selected="true" and an
unselected tab has aria-selected="false".
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>