Ajout des notification + page employé (#6)

| Numéro du ticket | Titre du ticket |
|------------------|-----------------|
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## 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/EmployeeContractPeriodManagerInterface.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service\Contracts;
+
+use App\Entity\Contract;
+use App\Entity\Employee;
+use App\Entity\EmployeeContractPeriod;
+use App\Enum\ContractNature;
+use DateTimeImmutable;
+
+interface EmployeeContractPeriodManagerInterface
+{
+    public function ensureContractPeriodExists(
+        Employee $employee,
+        Contract $contract,
+        DateTimeImmutable $startDate,
+        ?DateTimeImmutable $endDate,
+        ContractNature $nature,
+    ): void;
+
+    public function closeCurrentPeriod(
+        ?EmployeeContractPeriod $todayPeriod,
+        DateTimeImmutable $requestedEndDate,
+        bool $paidLeaveSettled,
+        ?string $comment = null
+    ): void;
+
+    public function createNextPeriod(
+        Employee $employee,
+        Contract $contract,
+        DateTimeImmutable $startDate,
+        ?DateTimeImmutable $endDate,
+        ContractNature $nature,
+        ?EmployeeContractPeriod $todayPeriod
+    ): void;
+}