- Backend Elo calculation (K=32/24/16 based on rating)
- Rating history recorded per game in rating_history table
- Profile updated with new rating + win/loss/draw counts
- Result screen shows actual rating change from server
- Board fills more available space (up to 500px)
- Carousel cards fixed: proper padding, no truncation, gradient previews
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>