- aria-labels on share links, sidebar social links and mobile nav icons
- aria-current on active nav links
- CopyButton: React state instead of innerHTML mutation, clipboard error
handling, accessible label and a polite live region for feedback
(Related code-block and image-caption a11y fixes landed with the
ImageWrapper/CodeWrapper rewrite in the previous perf commit.)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
