Feature: #107281 - Type-specific TCAdefaults support 

Description 

The TCAdefaults configuration has been extended to support type-specific syntax similar to TCEFORM, enabling different default values based on the record type.

This allows configuration like:

# Field-level default (applies to all content types)
TCAdefaults.tt_content.header_layout = 1

# Type-specific defaults (applies only to specific content types)
TCAdefaults.tt_content.header_layout.types.textmedia = 3
TCAdefaults.tt_content.frame_class.types.textmedia = ruler-before

The same syntax is supported in User TSconfig as well.

Type-specific defaults take precedence over field-level defaults, and Page TSconfig overrides User TSconfig following the established inheritance pattern.

Implementation details 

The feature is implemented in two main areas:

• Backend forms: The DatabaseRowInitializeNew class now processes type-specific defaults when creating new records in the backend.
• DataHandler: The DataHandler class supports type-specific defaults when creating records programmatically via the PHP API.

Fallback behavior 

If no type-specific default is found for a given record type, the system falls back to:

1. Field-level TCAdefaults configuration
2. TCA 'default' configuration
3. Database field default value

Automatic field discovery 

This enhancement makes TCAdefaults consistent with TCEFORM patterns and enables automatic field discovery.

Examples 

TCAdefaults.tt_content.header_layout = 1
TCAdefaults.tt_content.header_layout.types.textmedia = 3
TCAdefaults.tt_content.header_layout.types.image = 2

TCAdefaults.tt_content {
    header_layout = 1
    header_layout.types.textmedia = 3
    header_layout.types.image = 2

    frame_class = default
    frame_class.types.textmedia = ruler-before
    frame_class.types.image = none

    space_before_class = none
}

use TYPO3\CMS\Core\DataHandling\DataHandler;
use TYPO3\CMS\Core\Utility\GeneralUtility;

$dataHandler = GeneralUtility::makeInstance(DataHandler::class);
$datamap = [
    'tt_content' => [
        'NEW123' => [
            'pid' => 42,
            'CType' => 'textmedia',
            'header' => 'My Content Element',
            // header_layout and frame_class will be set automatically
            // based on type-specific TCAdefaults configuration
        ],
    ],
];
$dataHandler->start($datamap, [], $backendUser);
$dataHandler->process_datamap();

Impact 

This feature provides a more flexible and consistent way to configure default values for different record types, reducing repetitive configuration and improving the user experience when creating new records.

The type-specific syntax aligns TCAdefaults with the established TCEFORM pattern, making the configuration more intuitive for TYPO3 developers and integrators.