fix(model-types) : nullify weak references on ModelType delete

Belt-and-suspenders against orphan refs when a ModelType is deleted:
applicatively nullifies typeComposantId / typePieceId / typeProductId
on every "ON DELETE SET NULL" relationship before the row is removed,
in case the database FK cascade fails to fire.

Observed in prod 2026-04-28: deletion of ModelType "Paliers" left an
orphan in skeleton_subcomponent_requirements, surfacing as a 500 when
API Platform tried to lazy-load the missing proxy.

Co-Authored-By: RuFlo <ruv@ruv.net>

src/EventSubscriber/ModelTypeReferenceCleanupSubscriber.php

@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\EventSubscriber;
+
+use App\Entity\ModelType;
+use Doctrine\Bundle\DoctrineBundle\Attribute\AsDoctrineListener;
+use Doctrine\ORM\Event\PreRemoveEventArgs;
+use Doctrine\ORM\Events;
+
+use function sprintf;
+
+/**
+ * Belt-and-suspenders cleanup of weak references to a ModelType before deletion:
+ * runs the equivalent of every "ON DELETE SET NULL" cascade applicatively, in case
+ * the database FK fails to fire (observed on prod in 2026-04 — the deletion of
+ * ModelType "Paliers" left an orphan in skeleton_subcomponent_requirements).
+ */
+#[AsDoctrineListener(event: Events::preRemove)]
+final class ModelTypeReferenceCleanupSubscriber
+{
+    /** @var list<array{0: string, 1: string}> */
+    private const NULLABLE_REFERENCES = [
+        ['skeleton_subcomponent_requirements', 'typecomposantid'],
+        ['skeleton_piece_requirements', 'typepieceid'],
+        ['skeleton_product_requirements', 'typeproductid'],
+        ['composant_piece_slots', 'typepieceid'],
+        ['composant_product_slots', 'typeproductid'],
+        ['composant_subcomponent_slots', 'typecomposantid'],
+        ['piece_product_slots', 'typeproductid'],
+        ['machine_component_links', 'modeltypeid'],
+        ['machine_piece_links', 'modeltypeid'],
+        ['machine_product_links', 'modeltypeid'],
+    ];
+
+    public function preRemove(PreRemoveEventArgs $args): void
+    {
+        $entity = $args->getObject();
+        if (!$entity instanceof ModelType) {
+            return;
+        }
+
+        $id = $entity->getId();
+        if (!$id) {
+            return;
+        }
+
+        $conn = $args->getObjectManager()->getConnection();
+        foreach (self::NULLABLE_REFERENCES as [$table, $column]) {
+            $conn->executeStatement(
+                sprintf('UPDATE %s SET %s = NULL WHERE %s = ?', $table, $column, $column),
+                [$id],
+            );
+        }
+    }
+}