Fix: add missing db Session dependency to reset_section

backend/main.py

@@ -1933,6 +1933,7 @@ async def restore_backup(
 async def reset_section(
     section: str,
     current_user: User = Depends(get_current_admin),
+    db: Session = Depends(get_db),
 ):
     """Reset (truncate) a specific data section. Creates auto-backup first."""
     valid = {"attendance": AttendanceRecord, "holidays": Holiday, "leaves": LeaveRecord}