feat: answer received form submissions by mail

src/Controller/Admin/ApplicationFormSubmission/SendFollowUpMailController.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace App\Controller\Admin\ApplicationFormSubmission;
+
+use App\Email\ApplicationFormSubmissionMailer;
+use App\Entity\ApplicationFormSubmission;
+use App\Htmx\HxRedirectResponse;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\Routing\Attribute\Route;
+use Symfony\Component\Security\Http\Attribute\IsGranted;
+
+/**
+ * Sends the follow-up mail. Never automatic: a reviewer decides when a submission has waited long
+ * enough, and may send it again after a bounce or a wording fix - the stamp is overwritten.
+ *
+ * Unlike the receipt this one is allowed to fail loudly: somebody is watching the response.
+ */
+class SendFollowUpMailController extends AbstractController
+{
+    public function __construct(private readonly ApplicationFormSubmissionMailer $mailer)
+    {
+    }
+
+    #[Route('/admin/application-form-submission/send-follow-up/{uuid}', name: 'app_admin_application_form_submission_send_follow_up')]
+    #[IsGranted('ROLE_TEAM_ADMIN')]
+    public function index(ApplicationFormSubmission $submission, Request $request): Response
+    {
+        if (true === $request->isMethod(Request::METHOD_POST)) {
+            $this->mailer->sendFollowUp($submission);
+
+            $this->addFlash('success', 'Die zweite E-Mail wurde versendet');
+
+            return new HxRedirectResponse($this->generateUrl('app_admin_application_form_submission_detail', [
+                'uuid' => $submission->getUuid(),
+                'r' => $request->query->get('r'),
+            ]));
+        }
+
+        return $this->render('admin/application_form_submission/modal_send_follow_up.html.twig', [
+            'submission' => $submission,
+            // Named in the confirmation so a reviewer sees whether the handout the wording
+            // promises is actually going out.
+            'handout' => $this->mailer->findHandout(),
+        ]);
+    }
+}