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/blueprints/site.yml

@@ -12,6 +12,26 @@ columns:
         sortable: true
         create: false
         status: listed
+
+  - width: 1/2
+    fields:
+      siteTitle:
+        label: Titre du site
+        type: text
+        translate: true
+      siteTagline:
+        label: Tagline
+        type: text
+        translate: true
+      siteDescription:
+        label: Description
+        type: textarea
+        translate: true
+      logo:
+        label: Logo
+        type: files
+        max: 1
+
   - width: 1/2
     fields:
       contactEmail: