feat: unique email addresses of participants unless child, cleanup

addresses #869axbn21

src/Form/Service/ParticipantBulkInsuranceFieldHandler.php

@@ -56,7 +56,7 @@ class ParticipantBulkInsuranceFieldHandler extends AbstractParticipantFieldHandl
      * to dependent participants is handled by BookingDataProcessor during API submission.
      *
      * @param array<string, mixed> $submittedData    The submitted participant form data
-     * @param BookingDto  $bookingDto       The booking DTO to update
+     * @param BookingDto           $bookingDto       The booking DTO to update
      * @param int                  $participantIndex The index of the participant (must be 0)
      */
     public function processField(array $submittedData, BookingDto $bookingDto, int $participantIndex): void