Add logo upload to admin organizer edit page

Admin can now view the current logo and upload a new one via the
organizer edit form. Uses VichUploader with the existing organizer_logo
mapping. Adds test with fixture image.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/Controller/AdminControllerTest.php

@@ -509,6 +509,42 @@ class AdminControllerTest extends WebTestCase
         self::assertSame(0.5, $orga->getCommissionRate());
     }
 
+    public function testEditOrganizerWithLogo(): void
+    {
+        $client = static::createClient();
+        $em = static::getContainer()->get(EntityManagerInterface::class);
+        $admin = $this->createUser(['ROLE_ROOT']);
+        $orga = $this->createOrganizer($em);
+        $orga->setIsApproved(true);
+        $orga->setOffer('basic');
+        $orga->setCommissionRate(3.0);
+        $em->flush();
+
+        $logo = new \Symfony\Component\HttpFoundation\File\UploadedFile(
+            __DIR__.'/../fixtures/logo.png',
+            'logo.png',
+            'image/png',
+            null,
+            true,
+        );
+
+        $client->loginUser($admin);
+        $client->request('POST', '/admin/organisateur/'.$orga->getId().'/modifier', [
+            'first_name' => $orga->getFirstName(),
+            'last_name' => $orga->getLastName(),
+            'email' => $orga->getEmail(),
+            'company_name' => $orga->getCompanyName(),
+            'siret' => $orga->getSiret(),
+            'offer' => 'basic',
+            'commission_rate' => '3',
+        ], ['logo' => $logo]);
+
+        self::assertResponseRedirects('/admin/organisateurs?tab=approved');
+
+        $em->refresh($orga);
+        self::assertNotNull($orga->getLogoName());
+    }
+
     public function testEditOrganizerRedirectsIfNotApproved(): void
     {
         $client = static::createClient();