feat : add TagListProvider for listing registry tags

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/State/TagListProvider.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\State;
+
+use ApiPlatform\Metadata\Operation;
+use ApiPlatform\State\ProviderInterface;
+use App\ApiResource\TagList;
+use App\Repository\ApplicationRepository;
+use App\Service\GiteaRegistryService;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+
+final readonly class TagListProvider implements ProviderInterface
+{
+    public function __construct(
+        private ApplicationRepository $applicationRepository,
+        private GiteaRegistryService $giteaRegistryService,
+    ) {}
+
+    public function provide(Operation $operation, array $uriVariables = [], array $context = []): TagList
+    {
+        $slug = $uriVariables['slug'] ?? '';
+        $application = $this->applicationRepository->findOneBy(['slug' => $slug]);
+
+        if (null === $application) {
+            throw new NotFoundHttpException(sprintf('Application "%s" not found.', $slug));
+        }
+
+        $dto = new TagList();
+        $dto->tags = $this->giteaRegistryService->listTags($application->getRegistryImage());
+
+        return $dto;
+    }
+}