feat(seo): add SEO controller for robots.txt and sitemap.xml

- Implemented SeoController with methods for serving robots.txt and sitemap.xml.
- Updated robots.txt logic to disallow access to /admin and /api paths.
- Enhanced meta tags and Open Graph data in home.html.twig for better SEO.
- Added X-Robots-Tag header in SecurityHeadersSubscriber for /admin and /api routes.

src/Shared/Controller/SeoController.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace App\Shared\Controller;
+
+use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\Routing\Attribute\Route;
+
+class SeoController extends AbstractController
+{
+    #[Route('/robots.txt', name: 'seo_robots', methods: ['GET'])]
+    public function robots(Request $request): Response
+    {
+        if ($this->isStaging($request)) {
+            $body = "User-agent: *\nDisallow: /\n";
+        } else {
+            $base = $request->getSchemeAndHttpHost();
+            $body = "User-agent: *\n"
+                . "Disallow: /admin\n"
+                . "Disallow: /api\n"
+                . "Allow: /\n\n"
+                . "Sitemap: {$base}/sitemap.xml\n";
+        }
+
+        return new Response($body, Response::HTTP_OK, ['Content-Type' => 'text/plain; charset=UTF-8']);
+    }
+
+    #[Route('/sitemap.xml', name: 'seo_sitemap', methods: ['GET'])]
+    public function sitemap(Request $request): Response
+    {
+        $base = $request->getSchemeAndHttpHost();
+        $xml = '<?xml version="1.0" encoding="UTF-8"?>' . "\n"
+            . '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">' . "\n"
+            . '  <url>' . "\n"
+            . "    <loc>{$base}/</loc>\n"
+            . '    <changefreq>weekly</changefreq>' . "\n"
+            . '    <priority>1.0</priority>' . "\n"
+            . '  </url>' . "\n"
+            . '</urlset>' . "\n";
+
+        return new Response($xml, Response::HTTP_OK, ['Content-Type' => 'application/xml; charset=UTF-8']);
+    }
+
+    private function isStaging(Request $request): bool
+    {
+        $host = $request->getHost();
+
+        return str_ends_with($host, '.ddev.site')
+            || str_contains($host, 'localhost')
+            || str_starts_with($host, '127.0.0.1');
+    }
+}

src/Shared/EventSubscriber/SecurityHeadersSubscriber.php

@@ -29,6 +29,10 @@ class SecurityHeadersSubscriber implements EventSubscriberInterface
         if (str_starts_with($path, '/api') && !str_starts_with($path, '/api/doc')) {
             $response->headers->set('Content-Security-Policy', "default-src 'none'");
         }
+
+        if (str_starts_with($path, '/admin') || str_starts_with($path, '/api')) {
+            $response->headers->set('X-Robots-Tag', 'noindex, nofollow');
+        }
     }
 
     public static function getSubscribedEvents(): array