feat: admin view listing a travel's mailing recipients from bpn-connect

src/Form/Admin/TravelMailingLookupType.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Form\Admin;
+
+use App\Form\Model\TravelMailingLookupDto;
+use Symfony\Component\Form\AbstractType;
+use Symfony\Component\Form\Extension\Core\Type\TextType;
+use Symfony\Component\Form\FormBuilderInterface;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+
+/**
+ * Submits as GET with an empty block prefix, so a lookup is the plain URL `?travelCode=…`
+ * and can be bookmarked or shared.
+ *
+ * @extends AbstractType<TravelMailingLookupDto>
+ */
+class TravelMailingLookupType extends AbstractType
+{
+    public function buildForm(FormBuilderInterface $builder, array $options): void
+    {
+        $builder->add('travelCode', TextType::class, [
+            'label' => 'Reisecode',
+            'attr' => [
+                'placeholder' => 'z. B. LPJMP281126',
+            ],
+        ]);
+    }
+
+    public function configureOptions(OptionsResolver $resolver): void
+    {
+        $resolver->setDefaults([
+            'data_class' => TravelMailingLookupDto::class,
+            'method' => 'GET',
+            'csrf_protection' => false,
+        ]);
+    }
+
+    public function getBlockPrefix(): string
+    {
+        return '';
+    }
+}

src/Form/Model/TravelMailingLookupDto.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Form\Model;
+
+use Symfony\Component\Validator\Constraints as Assert;
+
+class TravelMailingLookupDto
+{
+    #[Assert\NotBlank(message: 'Bitte einen Reisecode angeben.')]
+    public ?string $travelCode = null;
+}