- Complete chess board with piece rendering (Unicode fallback)
- Drag-to-select + legal move highlights (gold dots)
- chess.js validation for all moves including promotion
- Game over detection (checkmate, stalemate, draw)
- Result overlay with "new game" option
- Board flip button
- Resign button
- Local play mode accessible from Play page
- Fix profile XP bar padding
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>