refactor: use Kirby page title for markers and add button tooltips

- Remove custom title field from marker.yml blueprint
- Use default Kirby page title for marker names in MarkerList
- Add French tooltips to MarkerList buttons (Ajouter, Modifier, Supprimer)
- API already uses page title via $marker->title()->value()

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

public/site/blueprints/pages/marker.yml

@@ -11,10 +11,6 @@ tabs:
           fields:
             type: fields
             fields:
-              title:
-                label: Titre du marqueur
-                type: text
-                required: true
               content:
                 label: Contenu
                 type: blocks