Important: #107594 - Icon overlay for TCA select items 

Description 

The ability to define an icon overlay for items in the "New Content Element" wizard was originally introduced in forge#92942 using Page TSconfig, but was accidentally removed during the web-component migration in forge#100065 and then restored in forge#105253.

In the meantime, forge#102834 added auto-registration of wizard items directly from TCA. Since icon overlays defined in Page TSconfig duplicate configuration that can now be specified in TCA, the recommended approach is to define icon overlays directly in TCA using the new iconOverlay option for select items.

The iconOverlay property is now supported in the SelectItem component, enabling icon overlays for wizard items that are auto-registered via TCA.

Impact 

Icon overlays for New Content Element Wizard items can now be defined directly in TCA alongside other item properties like icon, label, description, and group.

This consolidates configuration in a single location and eliminates the need for separate Page TSconfig definitions. Page TSconfig icon overlays remain supported for backward compatibility, but TCA-based configuration is now the recommended approach.

Migration 

Previous approach using Page TSconfig (still works, but no longer recommended):

mod.wizards.newContentElement.wizardItems {
    my_group.elements {
        my_element {
            iconIdentifier = content-header
            iconOverlay = actions-approve
            title = LLL:EXT:my_extension/Resources/Private/Language/locallang.xlf:my_element_title
            description = LLL:EXT:my_extension/Resources/Private/Language/locallang.xlf:my_element_description
            tt_content_defValues {
                CType = my_element
            }
        }
    }
}

Recommended approach using TCA:

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

ExtensionManagementUtility::addRecordType(
    [
        'label' => 'LLL:EXT:my_extension/Resources/Private/Language/locallang.xlf:my_element_title',
        'description' => 'LLL:EXT:my_extension/Resources/Private/Language/locallang.xlf:my_element_description',
        'value' => 'my_element',
        'icon' => 'content-header',
        'iconOverlay' => 'actions-approve',
        'group' => 'my_group'
    ],
    '...',
);