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/Indexer/ImportWorker.php

@@ -7,10 +7,11 @@ namespace MeshVault\Indexer;
 use MeshVault\Exception\PathSafetyException;
 use MeshVault\Indexer\Filesystem\PathSafety;
 use MeshVault\Indexer\SpaceChecker;
-use MeshVault\Repository\CatalogRepositoryInterface;
+use MeshVault\Catalog\CatalogServiceInterface;
 use MeshVault\Repository\ImportJobRepositoryInterface;
 use Psr\Log\LoggerInterface;
 use Throwable;
+use DomainException;
 
 /**
  * Serializes every managed-library mutation behind one advisory lock file and
@@ -32,7 +33,7 @@ final readonly class ImportWorker
     /** @param null|callable(): bool $shouldStop Consulted before each item. */
     public function __construct(
         private ImportJobRepositoryInterface $jobs,
-        private CatalogRepositoryInterface $catalog,
+        private CatalogServiceInterface $catalog,
         private StreamingHasher $hasher,
         private VerifiedCopier $copier,
         private StlValidator $validator,
@@ -112,20 +113,21 @@ final readonly class ImportWorker
             $published = $this->publish($plan, $destination);
             $relative = $this->relative($published);
             // Catalog and progress commit together, so a crash here simply replays.
-            $this->jobs->atomic(function () use ($item, $itemId, $plan, $published, $relative): void {
-                // Update managed_path to the actual published path (with collision suffix if any)
-                // so import_items.managed_path always points at the published file.
-                $this->jobs->updateManagedPath($itemId, $relative);
-                if ($item['model_id'] !== null) {
-                    $this->catalog->recordFile(
-                        (int) $item['model_id'],
+            $this->catalog->atomic(function () use ($item, $itemId, $plan, $relative): void {
+                // Catalog locks precede item/job locks on the shared PDO connection.
+                try {
+                    $this->catalog->registerFile(
+                        $item['model_id'] === null ? null : (int) $item['model_id'],
                         $relative,
                         $plan['hash'],
                         $plan['size'],
                         null,
                         'Present'
                     );
+                } catch (DomainException $error) {
+                    throw new ImportException('CATALOG_CONFLICT', $error->getMessage(), $error);
                 }
+                $this->jobs->updateManagedPath($itemId, $relative);
                 $this->jobs->finishItem($itemId, 'Completed');
             });
         } catch (Throwable $error) {