Seeds a two-block document via API (annotations.spec pattern) and drives the
keyboard: ? opens the cheatsheet, Esc closes it then a second Esc closes the
panel (Esc ladder), e toggles read/edit, and j/k walk the regions forward and
back. Adds an axe-core pass over the open dialog asserting no critical
violations and aria-modal.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>