Add TransitionHasSignerIfSignature validator

Introduced a new validator `TransitionHasSignerIfSignature` to enforce that a signature transition must have a designated signer. Included related tests, updated DTO annotations, and added translations for new validation messages.

src/Bundle/ChillMainBundle/Workflow/Validator/TransitionHasSignerIfSignatureValidator.php

@@ -0,0 +1,68 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\MainBundle\Workflow\Validator;
+
+use Chill\MainBundle\Entity\User;
+use Chill\MainBundle\Workflow\WorkflowTransitionContextDTO;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+use Symfony\Component\Workflow\Registry;
+
+final class TransitionHasSignerIfSignatureValidator extends ConstraintValidator
+{
+    public function __construct(
+        private readonly Registry $registry,
+    ) {}
+
+    public function validate($value, Constraint $constraint): void
+    {
+        if (!$constraint instanceof TransitionHasSignerIfSignature) {
+            throw new UnexpectedTypeException($constraint, TransitionHasSignerIfSignature::class);
+        }
+
+        if (!$value instanceof WorkflowTransitionContextDTO) {
+            throw new UnexpectedTypeException($value, WorkflowTransitionContextDTO::class);
+        }
+
+        if (null === $value->transition) {
+            return;
+        }
+
+        $workflow = $this->registry->get($value->entityWorkflow, $value->entityWorkflow->getWorkflowName());
+
+        foreach ($value->transition->getTos() as $to) {
+            $metadata = $workflow->getMetadataStore()->getPlaceMetadata($to);
+
+            if ([] !== ($metadata['isSignature'] ?? [])) {
+                if (null === $value->futureUserSignature && [] === $value->futurePersonSignatures) {
+                    $this->context->buildViolation($constraint->message)
+                        ->setCode($constraint->code)
+                        ->addViolation();
+
+                    return;
+                }
+
+                return;
+
+            }
+        }
+
+        // at this step, there is no signature in the To, we must check there is not users or persons
+        if ($value->futureUserSignature instanceof User || [] !== $value->futurePersonSignatures) {
+            $this->context->buildViolation($constraint->messageShouldBeEmpty)
+                ->setCode($constraint->code)
+                ->atPath($value->futureUserSignature instanceof User ? 'futureUserSignature' : 'futurePersonSignatures')
+                ->addViolation();
+        }
+    }
+}