feat: unique email addresses of participants unless child, cleanup

addresses #869axbn21

src/Service/ParticipantEligibilityService.php

@@ -32,7 +32,7 @@ class ParticipantEligibilityService
      * Results are cached per request to avoid redundant calculations.
      *
      * @param BookingDto $bookingDto       The current booking data
-     * @param int                 $participantIndex The index of the participant being evaluated
+     * @param int        $participantIndex The index of the participant being evaluated
      *
      * @return bool True if participant is eligible (has available skipasses)
      */