feat: publish unlisted GTIN tool

nginx.conf

@@ -64,6 +64,11 @@ server {
   location = /impressum.html { return 301 /impressum/; }
   location = /datenschutz.html { return 301 /datenschutz/; }
   location = /kontakt.html { return 301 /kontakt/; }
+  location = /gtin { return 301 /gtin/; }
+  location = /gtin/manifest.webmanifest {
+    default_type application/manifest+json;
+    try_files $uri =404;
+  }
   # /fotografie.html used to redirect to /shootings/; it resolves to its own
   # canonical page now instead of turning into a 404.
   location = /fotografie.html { return 301 /fotografie/; }