- Add accumulated_shortfall field to MatchModel to store historical shortfall at match completion
- Create Migration_040_AddAccumulatedShortfallToMatches for database schema update
- Update extraction flow in games_thread.py to store accumulated shortfall in match records
- Update sync report logic in client.py to use match's stored accumulated shortfall value
- Add test_last_sync_query.py to verify implementation
- Add CLIENT_SYNC_MINIMAL_PROMPT.md with API specifications

This ensures accurate reporting of cap compensation balance as it existed at the time each match was completed, rather than using the current global value.