Fix: champs camelCase + anglais, contact data, nettoyage debug

- Blueprint site.yml : renommage en camelCase (contactEmail, contactAddress, socialLinks, legalNotices)
- Controller site.php : mentionsLegales() → legalNotices(), fix (string) casts pour la sérialisation JSON
- state/site.svelte.js : ajout champ contact
- Menu.svelte : nouveau composant dialog pour le menu overlay
- Header.svelte : intégration Menu, animation hamburger CSS
- router/index.js : suppression des console.log de debug

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

site/controllers/site.php

@@ -24,6 +24,18 @@ return function ($page, $kirby, $site) {
           'name' => $l->name()
         ];
       })->values(),
+      'contact' => [
+        'email'       => (string)$site->contactEmail()->value(),
+        'address'     => (string)$site->contactAddress()->value(),
+        'socials'     => $site->socialLinks()->toStructure()->map(function($item) {
+          return [
+            'label' => (string)$item->label()->value(),
+            'url'   => (string)$item->url()->value(),
+            'picto' => (string)$item->picto()->value(),
+          ];
+        })->values(),
+        'legalNotice' => $site->legalNotices()->toFile()?->url(),
+      ],
       'navigation' => $navPages->map(function($p) use ($kirby) {
         $titles = [];
         foreach ($kirby->languages() as $lang) {