feat: add French language support with all article translations

- French Hugo config (languages.fr.toml)
- All 6 content pages translated: homepage, about, imprint, privacy,
  global overview article, France social media ban article
- Child-safety-map shortcode updated with French table + legend
- Nginx redirect updated to include /fr/ path
- CI smoke tests now verify /fr/ endpoint

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

nginx.conf

@@ -35,7 +35,7 @@ server {
     }
 
     # Redirect unprefixed paths to /en/
-    location ~ ^/(?!en/|de/|css/|js/|img/|favicon|android|apple|site|llms|health) {
+    location ~ ^/(?!en/|de/|fr/|css/|js/|img/|favicon|android|apple|site|llms|health) {
         return 302 /en$request_uri;
     }