feat(api) : add /api/health endpoint for monitoring

- Returns status, version, timestamp, PHP version, DB latency and memory usage
- Accessible without authentication (PUBLIC_ACCESS)
- Returns 200 when healthy, 503 when degraded (DB down)

config/packages/security.yaml

@@ -55,6 +55,7 @@ security:
         - { path: ^/api/admin, roles: ROLE_ADMIN }
         - { path: ^/api/docs, roles: PUBLIC_ACCESS }
         - { path: ^/api/test, roles: PUBLIC_ACCESS }
+        - { path: ^/api/health$, roles: PUBLIC_ACCESS }
         - { path: ^/docs, roles: PUBLIC_ACCESS }
         - { path: ^/contexts, roles: PUBLIC_ACCESS }
         - { path: ^/\.well-known, roles: PUBLIC_ACCESS }

src/Controller/HealthCheckController.php

@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Controller;
+
+use DateTimeImmutable;
+use DateTimeInterface;
+use Doctrine\DBAL\Connection;
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\JsonResponse;
+use Symfony\Component\Routing\Attribute\Route;
+use Throwable;
+
+class HealthCheckController extends AbstractController
+{
+    #[Route('/api/health', name: 'api_health', methods: ['GET'])]
+    public function __invoke(Connection $connection): JsonResponse
+    {
+        $version     = '0.0.0';
+        $versionFile = $this->getParameter('kernel.project_dir').'/VERSION';
+        if (file_exists($versionFile)) {
+            $version = trim(file_get_contents($versionFile));
+        }
+
+        $dbOk      = false;
+        $dbLatency = null;
+
+        try {
+            $start = hrtime(true);
+            $connection->executeQuery('SELECT 1');
+            $dbLatency = round((hrtime(true) - $start) / 1e6, 1);
+            $dbOk      = true;
+        } catch (Throwable) {
+        }
+
+        $healthy = $dbOk;
+
+        return $this->json([
+            'status'    => $healthy ? 'ok' : 'degraded',
+            'version'   => $version,
+            'timestamp' => new DateTimeImmutable()->format(DateTimeInterface::ATOM),
+            'php'       => PHP_VERSION,
+            'checks'    => [
+                'database' => [
+                    'status'     => $dbOk ? 'ok' : 'down',
+                    'latency_ms' => $dbLatency,
+                ],
+            ],
+            'memory_mb' => round(memory_get_usage(true) / 1024 / 1024, 1),
+        ], $healthy ? 200 : 503);
+    }
+}