Feature: #108832 - Introduce UserSettings object for backend user profile settings

Description

A new UserSettings object provides structured access to backend user profile settings defined via $GLOBALS['TYPO3_USER_SETTINGS'].

UserSettings Object

The UserSettings object can be retrieved via the backend user:

$userSettings = $GLOBALS['BE_USER']->getUserSettings();

// Check if a setting exists
if ($userSettings->has('colorScheme')) {
    $scheme = $userSettings->get('colorScheme');
}

// Get all settings as array
$allSettings = $userSettings->toArray();

// Typed access via dedicated methods
$emailOnLogin = $userSettings->isEmailMeAtLoginEnabled();
$showUploadFields = $userSettings->isUploadFieldsInTopOfEBEnabled();

The class implements \Psr\Container\ContainerInterface with has() and get() methods. The get() method throws UserSettingsNotFoundException if the setting does not exist.

New JSON Storage with Backward Compatibility

Profile settings are now stored in a new be_users.user_settings JSON field, providing a structured and queryable format. For backward compatibility, the existing serialized uc blob continues to be written alongside:

// Writing still uses the uc mechanism
$GLOBALS['BE_USER']->uc['colorScheme'] = 'dark';
$GLOBALS['BE_USER']->writeUC();
// Both uc (serialized) and user_settings (JSON) are updated

An upgrade wizard "Migrate user profile settings to JSON format" migrates existing settings from the uc blob to the new user_settings field.

Impact

Backend user profile settings can now be accessed via the UserSettings object, providing type safety and IDE support. The new JSON storage format improves data accessibility while maintaining full backward compatibility through dual-write to both storage formats.