feat: unique email addresses of participants unless child, cleanup

addresses #869axbn21

templates/booking/create/step_2.html.twig

@@ -2,7 +2,6 @@
 
 {% block content %}
     {% include '_partials/_flashes.html.twig' %}
-    <div {{ stimulus_controller('toast') }}></div>
     <h1>Neue Buchung</h1>
 
     <div class="grid grid-cols-3 gap-8">
@@ -37,11 +36,13 @@
             <div id="participant-cards-grid" class="space-y-4">
                 {% for cardData in cardsData %}
                     {% set hasErrors = loop.index0 in participantErrors|default([]) %}
+                    {% set errorMessages = participantErrorMessages[loop.index0]|default([]) %}
                     {% include 'booking/_participant_card.html.twig' with {
                         'cardData': cardData,
                         'index': loop.index0,
                         'mode': 'create',
-                        'hasErrors': hasErrors
+                        'hasErrors': hasErrors,
+                        'errorMessages': errorMessages
                     } %}
                 {% endfor %}
             </div>