- Add friend_messages table + chat.php API (send, history, unread)
- Add chat scene with real-time polling, day dividers, invite from chat
- Add game lobby scene (waiting room before match starts)
- Add "Challenge Friend" button on play home screen
- Add challenge-friend scene with friend picker + game/time selector
- Remove ad banner from chess, polish layout for all screen sizes
- Fix Ludo layout (broken #ludo-wrap div, board now fills space properly)
- Route invite acceptance through lobby instead of direct game push
- Add 💬 chat button on friend cards in social scene
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>