Refactor Base64 encoding/decoding methods for consistency, update controller routes, and improve CI configuration

src/Controller/PrepareEliminationController.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Controller;
+
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\Routing\Attribute\Route;
+
+#[Route(path: '/backoffice/elimination')]
+final class PrepareEliminationController extends AbstractController
+{
+    #[Route('/prepare', name: 'app_prepare_elimination')]
+    public function index(): Response
+    {
+        return $this->render('prepare_elimination/index.html.twig', [
+            'controller_name' => 'PrepareEliminationController',
+        ]);
+    }
+}