BUG-004 – Available copies exceed total copies

[KaremFtayyeh]

Title: Available copies can exceed total book copies
Description:
Returning books can increase the available copies beyond the configured total copies, causing inconsistent inventory data.
Steps to Reproduce:

1. Find a book that currently shows 5/5 copies available.
2. Process another return for that same book.
3. Refresh the book details.
   Expected Result:
   Available copies remain capped at the total (e.g., 5/5) or extra return is rejected.
   Actual Result:
   Available copies become 6/5.
   Severity: High
   Priority: P1
   Status: New
   Environment: Chrome 129, Windows 11
   Screenshot / Evidence: