Added comprehensive keyboard shortcuts overlay modal and missing shortcuts
for the replay viewer:
- New keyboard shortcuts overlay (activated by ? or / key) showing all
available shortcuts in an accessible modal dialog
- Added missing shortcuts: V (cycle view mode), E (toggle event timeline),
C (toggle commentary), Shift+arrows (jump 10 turns)
- Updated visible shortcuts list in sidebar to include all shortcuts
- Modal is fully accessible with ARIA roles, keyboard navigation, and
respects prefers-reduced-motion
- All shortcuts are WCAG 2.1 Level AA compliant
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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