feat: replace date field for participant's birthday

src/Form/BookingParticipantType.php

@@ -166,9 +166,16 @@ class BookingParticipantType extends AbstractType
             ], $getFieldState('lastName')))
             ->add('dateOfBirth', BirthdayType::class, $this->mergeFieldState([
                 'label' => 'Geburtsdatum',
-                'html5' => true,
-                'widget' => 'single_text',
+                'widget' => 'text',
                 'input' => 'datetime_immutable',
+                'attr' => [
+                    'class' => 'flex items-center space-x-2',
+                ],
+                'placeholder' => [
+                    'year' => 'Jahr',
+                    'month' => 'Monat',
+                    'day' => 'Tag',
+                ],
             ], $getFieldState('dateOfBirth')))
             ->add('gender', ChoiceType::class, $this->mergeFieldState([
                 'label' => 'Geschlecht',

src/Form/Service/ParticipantDateOfBirthFieldHandler.php

@@ -76,7 +76,14 @@ class ParticipantDateOfBirthFieldHandler extends AbstractParticipantFieldHandler
      * Normalizes a date value from form submission to DateTimeImmutable or null.
      *
      * This method handles the conversion of form date values to proper DateTimeImmutable
-     * objects. It gracefully handles empty strings, null values, and invalid date formats.
+     * objects. It gracefully handles empty strings, null values, invalid date formats,
+     * and array input from multi-field date widgets (BirthdayType).
+     *
+     * Supported input formats:
+     * - Array: ['year' => int, 'month' => int, 'day' => int] from BirthdayType
+     * - DateTimeInterface: Already converted DateTime objects
+     * - String: ISO date strings or any format parseable by DateTimeImmutable
+     * - Null/empty: No date selected
      *
      * @param mixed $value The raw value from form submission
      *
@@ -84,18 +91,50 @@ class ParticipantDateOfBirthFieldHandler extends AbstractParticipantFieldHandler
      */
     private function normalizeDateValue(mixed $value): ?\DateTimeImmutable
     {
-        // Handle null or empty string (no date selected)
-        if (null === $value || '' === trim((string) $value)) {
+        // Handle null first
+        if (null === $value) {
             return null;
         }
 
+        // Handle array input from multi-field date widget (BirthdayType)
+        if (true === is_array($value)) {
+            // Check if all required fields are present and valid
+            if (false === isset($value['year'], $value['month'], $value['day'])
+                || '' === trim((string) ($value['year'] ?? ''))
+                || '' === trim((string) ($value['month'] ?? ''))
+                || '' === trim((string) ($value['day'] ?? ''))
+            ) {
+                return null;
+            }
+
+            try {
+                // Create date string in ISO format (YYYY-MM-DD)
+                $dateString = sprintf(
+                    '%04d-%02d-%02d',
+                    (int) $value['year'],
+                    (int) $value['month'],
+                    (int) $value['day']
+                );
+
+                return new \DateTimeImmutable($dateString);
+            } catch (\Exception $e) {
+                // Invalid date components (e.g., Feb 31, invalid year)
+                return null;
+            }
+        }
+
         // If already a DateTimeInterface, convert to DateTimeImmutable
         if ($value instanceof \DateTimeInterface) {
             return \DateTimeImmutable::createFromInterface($value);
         }
 
-        // Try to parse string date
-        if (is_string($value)) {
+        // Handle string date (including empty string check)
+        if (true === is_string($value)) {
+            // Empty string means no date selected
+            if ('' === trim($value)) {
+                return null;
+            }
+
             try {
                 return new \DateTimeImmutable($value);
             } catch (\Exception $e) {