- Rename START_GAMES message type to SCHEDULE_GAMES for clarity
- Add schedule_games() method to MessageBuilder class
- Update all references in games_thread.py, match_timer.py, routes.py, and tests
- Improve message naming consistency:
  * START_GAME: Actually starts games/timers
  * SCHEDULE_GAMES: Changes status to scheduled (doesn't start timer)
- All message types now follow consistent naming convention
- Fixes potential confusion between starting and scheduling actions