Fix Check stock availability Issue and Add error message

- Added "Check Stock Availability" header in AdminMenu::checkStockAvailability for clarity.
- Updated prompt text to "Enter the Item ID" for consistency.
- Added util::clear() after reading Item ID to refresh the screen before displaying results.
- Implemented validation to show "Item not Found" message when the entered ID does not exist in inventory.
Fix #1741

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/AdminMenu.cpp

@@ -298,8 +298,10 @@ void AdminMenu::checkStockAvailability()
 {
 	util::clear();
 	std::string itemId;
-	std::cout << "Enter the Item Id : ";
+	std::cout << "Check Stock Availability \n";
+	std::cout << "Enter the Item ID : ";
 	util::read(itemId);
+	util::clear();
 	const InventoryItem* selectedItem = m_controller.getInventoryItem(itemId);
 	if (selectedItem != nullptr)
 	{
@@ -312,6 +314,10 @@ void AdminMenu::checkStockAvailability()
 			std::cout << "Quantity     : " << selectedItem->getQuantity() << "\n";
 		}
 	}
+	else
+	{
+		std::cout << "Item not Found" << std::endl;
+	}
 	util::pressEnter();
 }