fix: cleanup and small improvements

- added empty check in inventory alerts
- corrected parts cost calculation
- removed unused getUser method
- updated default admin password
- fixed missing includes in menus
- cleaned up MenuHelper comments

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/InventoryManagementService.cpp

@@ -59,6 +59,10 @@ Returns:
 void InventoryManagementService::sendLowStockAlerts()
 {
 	auto& inventoryItems = m_dataStore.getInventoryItems();
+	if (inventoryItems.isEmpty())
+	{
+		return;
+	}
 	int inventoryItemsSize = inventoryItems.getSize();
 	auto& usersMap = m_dataStore.getUsers();
 	int usersMapSize = usersMap.getSize();

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/PaymentManagementService.cpp

@@ -315,7 +315,7 @@ void PaymentManagementService::generateInvoice(ServiceBooking* booking)
 		{
 			createInventoryItemsMap(completeInventoryItemMapOfBooking, currentService);
 			totalLabourCost += currentService->getLaborCost();
-			totalPartsCost += calculatePartsCost(currentService);
+			totalPartsCost += util::calculatePartsCost(currentService);
 		}
 	}
 	totalServiceCost = totalLabourCost + totalPartsCost;

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/UserManagementService.cpp

@@ -305,18 +305,4 @@ util::Map<std::string, User*> UserManagementService::getUsers(util::UserType typ
 		}
 	}
 	return filteredUsersMap;
-}
-
-User* UserManagementService::getUser(const std::string& userID)
-{
-	util::Map<std::string, User*>& currentUsers = m_dataStore.getUsers();
-	for (int iterator = 0; iterator < currentUsers.getSize(); iterator++)
-	{
-		User* currentUser = currentUsers.getValueAt(iterator);
-		if (currentUser->getId() == userID)
-		{
-			return currentUser;
-		}
-	}
-	return nullptr;
-}
+}