feat: endpoint FetchMangaChapters et tests

src/Domain/Manga/Infrastructure/Persistence/LegacyMangaRepository.php

@@ -126,6 +126,34 @@ readonly class LegacyMangaRepository implements MangaRepositoryInterface
             ->getSingleScalarResult();
     }
 
+    public function findByExternalId(ExternalId $externalId): ?DomainManga
+    {
+        $entity = $this->entityManager->getRepository(EntityManga::class)->findOneBy([
+            'externalId' => $externalId->getValue()
+        ]);
+        
+        return $entity ? $this->toDomain($entity) : null;
+    }
+
+    public function saveChapter(Chapter $chapter): void
+    {
+        $manga = $this->entityManager->find(EntityManga::class, $chapter->getMangaId());
+        
+        if (!$manga) {
+            throw new \RuntimeException('Manga not found');
+        }
+
+        $entity = new EntityChapter();
+        $entity->setManga($manga)
+            ->setNumber($chapter->getNumber())
+            ->setTitle($chapter->getTitle())
+            ->setVolume($chapter->getVolume())
+            ->setVisible($chapter->isVisible());
+
+        $this->entityManager->persist($entity);
+        $this->entityManager->flush();
+    }
+
     private function toDomain(EntityManga $entity): DomainManga
     {
         return new DomainManga(