feat: catalog shared contracts (Tasks 1-4)

Task 1: Establish catalog identity and atomic file ownership
- CatalogService, CatalogServiceInterface, ModelMetadata DTO
- PdoCatalogRepository with atomic operations, savepoint support
- FOR UPDATE file locks in ascending order, FOR NO KEY UPDATE for metadata
- FK-compatible lock composition documented (spec §6)

Task 2: M3 import & indexing engine delivery layer
- ImportService, ImportWorker with durable collision handling
- SpaceChecker, StreamingHasher, VerifiedCopier, StlValidator
- FileEnumerator, LocalFilesystem, PathSafety
- Console command wiring via ContainerWiringTest

Task 3: Importer integration and repair
- LegacyGuessedImportGroupingAdapter isolates first-directory guessing
- ImportService uses adapter; ImportWorker uses CatalogServiceInterface
- Null owners remain null; DomainException mapped to CATALOG_CONFLICT
- SQL failure after registration/path update with caller sentinel rollback

Task 4: PostgreSQL contention evidence and bounded acceptance
- 6 new PostgresCatalogContractsTest cases with independent sessions
- Generated schemas, 250ms lock timeouts, 5s statement timeouts
- Ascending file locks, FOR SHARE contention, stale-owner rejection
- Rollback/retry, nested transaction survival, root creation contention
- Negative controls: replay FOR UPDATE removal (11 failures), metadata FOR UPDATE (4 FK KEY SHARE timeouts)
- Fresh Docker PostgreSQL 17 / PHP 8.4.26: 473 tests, 2718 assertions, 10 skips, exit 0

All local: 474 tests, 2347 assertions, 54 skips, foundation/lint clean.

src/Catalog/CatalogService.php

@@ -6,12 +6,54 @@ namespace MeshVault\Catalog;
 
 use MeshVault\Repository\CatalogRepositoryInterface;
 
-final class CatalogService
+final class CatalogService implements CatalogServiceInterface
 {
     public function __construct(private readonly CatalogRepositoryInterface $catalog)
     {
     }
 
+    /** @see CatalogServiceInterface::atomic() for supported lock-order compositions. */
+    public function atomic(callable $operation): mixed
+    {
+        return $this->catalog->atomic($operation);
+    }
+
+    public function modelMetadata(int $modelId): ?array
+    {
+        return $this->catalog->modelMetadata($modelId);
+    }
+
+    public function updateModelMetadata(int $modelId, array $expected, array $replacement): array
+    {
+        return $this->catalog->updateModelMetadata($modelId, $expected, $replacement);
+    }
+
+    public function changeFileStatus(int $fileId, string $expectedStatus, string $targetStatus): array
+    {
+        return $this->catalog->changeFileStatus($fileId, $expectedStatus, $targetStatus);
+    }
+
+    public function file(int $fileId): ?array
+    {
+        return $this->catalog->file($fileId);
+    }
+
+    public function fileByManagedPath(string $managedPath): ?array
+    {
+        return $this->catalog->fileByManagedPath($managedPath);
+    }
+
+    public function registerFile(
+        ?int $modelId,
+        string $managedPath,
+        string $hash,
+        int $size,
+        ?string $mime = null,
+        string $status = 'Present'
+    ): int {
+        return $this->catalog->recordFile($modelId, $managedPath, $hash, $size, $mime, $status);
+    }
+
     public function createModel(string $folderPath, string $modelName): int
     {
         return $this->catalog->atomic(fn (): int => $this->catalog->createModel($folderPath, $modelName));