feat: show placeholders for individual date parts in date of birth field

templates/forms.html.twig

@@ -194,6 +194,27 @@
     </div>
 {%- endblock multiselect_widget -%}
 
+{%- block birthday_widget -%}
+    {%- set placeholders = {
+        'day': 'Tag',
+        'month': 'Monat',
+        'year': 'Jahr'
+    } -%}
+    {%- set field_order = ['day', 'month', 'year'] -%}
+    <div {{ block('widget_container_attributes') }}>
+        {%- for field_name in field_order -%}
+            {%- set child = form[field_name] -%}
+            {%- set child_attr = child.vars.attr|default({}) -%}
+            {%- set child_attr = child_attr|merge({
+                'placeholder': placeholders[field_name],
+                'class': (child_attr.class|default('') ~ ' form-field')|trim
+            }) -%}
+
+            {{- form_widget(child, {'attr': child_attr}) -}}
+        {%- endfor -%}
+    </div>
+{%- endblock birthday_widget -%}
+
 {% block insurance_choice_widget %}
     {%- if expanded -%}
         {%- for child in form %}