- Remove Socket.IO dependency, server multiplayer logic (lobby, room management), and client-side socket service
- Replace multiplayer-only flow with single-player AI gameplay; add `OpponentSelectScene` for AI configuration
- Simplify game registry to use `minOpponents`/`maxOpponents` instead of `supportsMultiplayer`/`multiplayerOnly`
- Update game registration to remove multiplayer flags and adjust `games` table schema to hardcode `supports_multiplayer = 0`
- Remove `SOCKET_IO_CORS_ORIGIN` from environment configuration
- Update documentation to reflect single-player architecture and simplified game creation process
- Fix minor UI issues: add width to buttons in auth scenes, fix auth listener cleanup in LandingScene, restore DOM layer visibility in Modal
Brian Fertig