Add user entity and OAuth2 authentication with room lobbies#196

ArthurJCQ merged 30 commits intomainArthurJCQ/KillerAPI:mainfrom

claude/user-entity-oauth-players-011CUvLt3TNszkFNyoQpYueGArthurJCQ/KillerAPI:claude/user-entity-oauth-players-011CUvLt3TNszkFNyoQpYueGCopy head branch name to clipboard