Fix: camelCase cohérent dans blueprint et contrôleur

- Blueprint : ajout siteTitle, siteTagline, siteDescription, logo
- Contrôleur : site_title() → siteTitle()

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

site/controllers/site.php

@@ -14,7 +14,7 @@ return function ($page, $kirby, $site) {
     'template' => $page->intendedTemplate()->name(),
     'modified' => $page->modified('Y-m-d'),
     'site' => [
-      'title' => $site->site_title()->value(),
+      'title' => $site->siteTitle()->value(),
       'url' => $site->url(),
       'logo' => $site->logo()->toFile()?->url(),
       'language' => $kirby->language()?->code() ?? 'fr',