Ajout des notification + page employé (#6)

| Numéro du ticket | Titre du ticket |
|------------------|-----------------|
|                  |                 |

## Description de la PR

## Modification du .env

## Check list

- [ ] Pas de régression
- [ ] TU/TI/TF rédigée
- [ ] TU/TI/TF OK
- [ ] CHANGELOG modifié

Reviewed-on: #6
Co-authored-by: tristan <tristan@yuno.malio.fr>
Co-committed-by: tristan <tristan@yuno.malio.fr>

src/Service/Contracts/EmployeeContractChangeRequestFactory.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service\Contracts;
+
+use App\Entity\Employee;
+use App\Enum\ContractNature;
+use DateTimeImmutable;
+use Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException;
+
+final class EmployeeContractChangeRequestFactory
+{
+    public function fromEmployee(Employee $employee): EmployeeContractChangeRequest
+    {
+        return new EmployeeContractChangeRequest(
+            contractNature: $this->resolveContractNature($employee->getContractNature()),
+            contractStartDate: $this->parseOptionalYmd($employee->getContractStartDate(), 'contractStartDate'),
+            contractEndDate: $this->parseOptionalYmd($employee->getContractEndDate(), 'contractEndDate'),
+            contractPaidLeaveSettled: $employee->getContractPaidLeaveSettled(),
+            contractComment: $employee->getContractComment(),
+        );
+    }
+
+    private function resolveContractNature(?string $raw): ?ContractNature
+    {
+        if (null === $raw || '' === trim($raw)) {
+            return null;
+        }
+
+        return ContractNature::tryFrom(trim($raw))
+            ?? throw new UnprocessableEntityHttpException('contractNature must be one of CDI, CDD, INTERIM.');
+    }
+
+    private function parseOptionalYmd(?string $raw, string $field): ?DateTimeImmutable
+    {
+        if (null === $raw || '' === trim($raw)) {
+            return null;
+        }
+
+        $value = trim($raw);
+        $date  = DateTimeImmutable::createFromFormat('Y-m-d', $value);
+        if (!$date || $date->format('Y-m-d') !== $value) {
+            throw new UnprocessableEntityHttpException(sprintf('%s must use Y-m-d format.', $field));
+        }
+
+        return $date;
+    }
+}