feat: offer a newsletter opt-in for the other participants

addresses #869etn6c5

src/Form/BookingCreateStep4Type.php

@@ -44,6 +44,17 @@ class BookingCreateStep4Type extends AbstractType
             ]);
         }
 
+        if (true === $options['show_companion_newsletter_opt_in']) {
+            // Deliberately no companion addresses in the label: the applicant already knows them,
+            // and rendering them would put other people's addresses on a shared screen.
+            $builder->add('companionNewsletterOptIn', CheckboxType::class, [
+                'label' => 'Ich möchte auch meine Mitfahrer:innen für den E&P Newsletter anmelden.',
+                'help' => 'Alle erhalten eine eigene Bestätigungs-E-Mail und werden erst nach ihrer eigenen Bestätigung angemeldet.',
+                'mapped' => false,
+                'required' => false,
+            ]);
+        }
+
         $builder
             ->add('confirmationAccepted', CheckboxType::class, [
                 'label' => 'Ich bestätige, dass alle Angaben korrekt sind und möchte verbindlich buchen.',
@@ -72,10 +83,12 @@ class BookingCreateStep4Type extends AbstractType
         $resolver->setDefaults([
             'data_class' => BookingDto::class,
             'show_newsletter_opt_in' => false,
+            'show_companion_newsletter_opt_in' => false,
             'newsletter_target_email' => null,
         ]);
 
         $resolver->setAllowedTypes('show_newsletter_opt_in', 'bool');
+        $resolver->setAllowedTypes('show_companion_newsletter_opt_in', 'bool');
         $resolver->setAllowedTypes('newsletter_target_email', ['null', 'string']);
     }
 }