refactor start form

app/views/start_form/private.html.erb

@@ -4,7 +4,7 @@
 <% end %>
 <main class="max-w-md space-y-6 mx-auto px-2 mt-12 mb-4">
   <div class="text-center w-full space-y-6">
-    <%= render 'banner' %>
+    <%= render 'start_form/banner' %>
     <p class="text-xl font-semibold text-center">
       <%= t('share_link_is_currently_disabled') %>
     </p>