- Add requires_full_sync flag to /api/reports/sync response when no records exist for client across ALL report tables (bets, extraction_stats, match_reports)
- Add requires_full_sync flag to /api/reports/last-sync response when no records exist for client
- Update REPORTS_SYNC_PROTOCOL_DOCUMENTATION.md with full sync required scenario
- Update REPORTS_SYNC_API_SPECIFICATION.txt with requires_full_sync field documentation
- Create REPORTS_SYNC_EMPTY_DATABASE_FIX.md with comprehensive fix documentation

This fix addresses the critical gap where the server couldn't signal when it required a full sync after database reset, ensuring automatic recovery without manual intervention.