Reflect backend audit findings in TODO.md:
- 12 REST endpoints documented for player, match, matches, and sitemap
- Data models aligned with backend schemas (Match, Player, MatchPlayer,
etc.)
- CS2 compatibility confirmed with Premier rating support (0-30000)
Add comprehensive API documentation covering:
- Endpoint specifications and response structures
- Integration guide with TypeScript examples
- Error handling and caching strategies
- CS2 migration notes for rank system and MR12 changes
