📢 Update: Billing system optimization

🔹 Improvements and Fixes:

🛡️ Improved parameter security in giveBillingItem and payBill functions to prevent exploits.

🔍 Added amount checks to avoid negative or non-numeric values.

🚀 Optimized event handling for better stability.

✅ Drop system fix: items can now not be mistakenly transferred to a prohibited inventory.

Fixes #[issue_no]

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Does your submission pass tests?

Please describe the changes this PR makes and why it should be merged:

Discord username (if different from GitHub):