feat: unique email addresses of participants unless child, cleanup

addresses #869axbn21

src/Form/Service/Condition/ApplicantCondition.php

@@ -21,7 +21,7 @@ class ApplicantCondition implements FieldConditionInterface
     /**
      * Evaluates if the participant is the applicant.
      *
-     * @param BookingDto  $bookingDto       The current booking data (create or edit)
+     * @param BookingDto           $bookingDto       The current booking data (create or edit)
      * @param int                  $participantIndex The index of the participant being evaluated
      * @param array<string, mixed> $formData         Current form data (unused)
      *