feat(reference-auto) : add automatic reference generation for pieces

ModelType defines a formula with placeholders ({serie}{diametre}{type}).
ReferenceAutoGenerator resolves it from CustomFieldValues with trim+uppercase normalisation.
ReferenceAutoSubscriber (onFlush) recalculates on Piece/CFV insert/update/delete.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Service/ReferenceAutoGenerator.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service;
+
+use App\Entity\CustomFieldValue;
+use App\Entity\Piece;
+
+class ReferenceAutoGenerator
+{
+    public function generate(Piece $piece): ?string
+    {
+        $modelType = $piece->getTypePiece();
+
+        if (!$modelType || !$modelType->getReferenceFormula()) {
+            return null;
+        }
+
+        $valueMap = $this->buildValueMap($piece);
+
+        $requiredFields = $modelType->getRequiredFieldsForReference();
+
+        if ($requiredFields) {
+            foreach ($requiredFields as $fieldName) {
+                if (!isset($valueMap[$fieldName]) || '' === $valueMap[$fieldName]) {
+                    return null;
+                }
+            }
+        }
+
+        return preg_replace_callback('/\{(\w+)\}/', static function (array $matches) use ($valueMap): string {
+            return $valueMap[$matches[1]] ?? '';
+        }, $modelType->getReferenceFormula());
+    }
+
+    /**
+     * Build a map of fieldName → normalized value from the Piece's CustomFieldValues.
+     *
+     * @return array<string, string>
+     */
+    private function buildValueMap(Piece $piece): array
+    {
+        $map = [];
+
+        /** @var CustomFieldValue $cfv */
+        foreach ($piece->getCustomFieldValues() as $cfv) {
+            $normalized                             = mb_strtoupper(trim($cfv->getValue()));
+            $map[$cfv->getCustomField()->getName()] = $normalized;
+        }
+
+        return $map;
+    }
+}