feat: implement hx-boost for reliable loading indication

templates/booking/create/step_3.html.twig

@@ -4,11 +4,7 @@
     {{ form_start(form, {
         'attr': {
             'class': 'flex-1 flex flex-col min-h-0',
-            'novalidate': 'novalidate',
-            'hx-post': path('app_booking_create_step_3'),
-            'hx-target': '#form-wrapper',
-            'hx-select': '#form-wrapper',
-            'hx-swap': 'outerHTML'
+            'novalidate': 'novalidate'
         }
     }) }}
         {# Pagination - mobile only (above summary) #}
@@ -82,7 +78,7 @@
                         class="inline-flex items-center justify-center bg-gray-200 rounded-md w-10 h-10">
                     <svg class="w-8 h-8" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><rect width="256" height="256" fill="none"/><line x1="200" y1="56" x2="56" y2="200" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round" stroke-width="16"/><line x1="200" y1="200" x2="56" y2="56" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round" stroke-width="16"/></svg>
                 </button>
-                <button type="submit" class="button button--primary" {{ qa_attribute('btn-submit') }} {{ stimulus_action('loading', 'show') }}>
+                <button type="submit" class="button button--primary" {{ qa_attribute('btn-submit') }}>
                     Weiter zu Schritt 4
                 </button>
             </div>