Fixed:
- Item duplication bug after server restarts
- Players able to claim items multiple times
- Database and memory synchronization issues
- Race conditions in collection system
- Backwards logic in database verification
- Duplicate checking only working for 5 seconds
- Batch item saves failing without rollback
- Thread safety issues in collection GUI
- Items added to memory before database confirmation

Improved:
- Transaction safety for all database operations
- Duplicate detection now works across all methods
- Database is now single source of truth
- Better error logging for sync issues