feat(mail) : MailTestConnectionController — POST /api/mail/configuration/test

- endpoint ROLE_ADMIN qui teste la connexion IMAP via listFolders
- retourne ok:bool + foldersCount ou error sanitise (pas de leak interne)
- priority:1 obligatoire pour eviter conflit avec route API Platform {id}

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Controller/Mail/MailTestConnectionController.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Controller\Mail;
+
+use App\Mail\Exception\MailProviderException;
+use App\Mail\MailProviderInterface;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\JsonResponse;
+use Symfony\Component\Routing\Attribute\Route;
+use Symfony\Component\Security\Http\Attribute\IsGranted;
+use Throwable;
+
+#[Route('/api/mail/configuration/test', name: 'mail_configuration_test', methods: ['POST'], priority: 1)]
+#[IsGranted('ROLE_ADMIN')]
+class MailTestConnectionController extends AbstractController
+{
+    public function __construct(
+        private readonly MailProviderInterface $mailProvider,
+    ) {}
+
+    public function __invoke(): JsonResponse
+    {
+        try {
+            $folders = $this->mailProvider->listFolders();
+
+            return $this->json([
+                'ok'           => true,
+                'foldersCount' => count($folders),
+            ]);
+        } catch (MailProviderException) {
+            return $this->json([
+                'ok'    => false,
+                'error' => 'Connexion IMAP impossible. Vérifiez la configuration.',
+            ]);
+        } catch (Throwable) {
+            return $this->json([
+                'ok'    => false,
+                'error' => 'Erreur inattendue lors du test de connexion.',
+            ]);
+        }
+    }
+}