feat(a11y,perf): comprehensive icon button labels, toolbar a11y, timeline binary search
A11y C-1: aria-label on 30+ remaining icon-only buttons across:
- settings panels (close, reset, info, expand, remove, undo)
- editor toolbar (bold, italic, underline, strike, code, spoiler,
blockquote, code block, ordered/unordered list, headings 1-3)
- auth stages (cancel buttons in SSO, Password stages)
- device verification (cancel buttons)
- password input (show/hide toggle with dynamic label)
- event readers, account data editor close buttons
- global emoji packs (add/remove buttons)
Perf-5: Replace O(N×T) getTimelineAndBaseIndex scan with precomputed binary
search (timelineSegments useMemo) — O(log T) per visible message render
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Lotus Bot
4e80c0a0f5