Refactor routes to use cleaner URL structure with order_id parameter

app/views/orders/new.html.erb

@@ -89,7 +89,7 @@
             <p class="text-gray-600 max-w-md mx-auto">Veuillez fournir les prénoms et noms des personnes qui utiliseront les billets.</p>
           </div>
 
-          <%= form_with url: event_order_create_path(@event.slug, @event.id), method: :post, local: true, class: "space-y-8" do |form| %>
+          <%= form_with url: order_create_path(@event.slug, @event.id), method: :post, local: true, class: "space-y-8" do |form| %>
             <div class="space-y-6">
               <div class="flex items-center justify-center mb-2">
                 <div class="bg-purple-600 rounded-full p-2 mr-3">