feat: Implement active games cleanup task and enhance bait management

- Added a background task to clean up active games every 15 minutes in Multiplayer.py to prevent stuck games.
- Enhanced set_active_bait method in db.py to clear active bait when bait_id is None.
- Improved logging for bait management, including current and final state verification.
- Introduced upgrade_interest_with_item method to allow interest level upgrades without cost.
- Added add_to_inventory method to streamline item addition to user inventory with clean item structure.

Author: siqnole