feat(categories) : add bidirectional piece/component category conversion

Backend service and controller for converting piece categories to component
categories (and vice-versa). Uses raw SQL in a transaction to preserve IDs
and transfer all related data (documents, custom fields, constructeurs).
Includes php-cs-fixer formatting pass on existing controllers/entities.

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

src/EventSubscriber/PieceProductSyncSubscriber.php

@@ -16,9 +16,7 @@ use Doctrine\ORM\Events;
  */
 final class PieceProductSyncSubscriber implements EventSubscriber
 {
-    public function __construct(private readonly ProductRepository $productRepository)
-    {
-    }
+    public function __construct(private readonly ProductRepository $productRepository) {}
 
     public function getSubscribedEvents(): array
     {
@@ -47,7 +45,7 @@ final class PieceProductSyncSubscriber implements EventSubscriber
 
         $this->syncPrimaryProduct($entity);
 
-        $em = $args->getObjectManager();
+        $em   = $args->getObjectManager();
         $meta = $em->getClassMetadata(Piece::class);
         $em->getUnitOfWork()->recomputeSingleEntityChangeSet($meta, $entity);
     }
@@ -56,7 +54,7 @@ final class PieceProductSyncSubscriber implements EventSubscriber
     {
         $productIds = $piece->getProductIds();
 
-        if ($productIds === []) {
+        if ([] === $productIds) {
             // If no explicit list is provided, keep the legacy relation as-is.
             return;
         }
@@ -77,4 +75,3 @@ final class PieceProductSyncSubscriber implements EventSubscriber
         $piece->setProduct($primaryProduct);
     }
 }
-