feat: implement hx-boost for reliable loading indication

templates/booking/_form_theme.html.twig

@@ -37,6 +37,7 @@
                 {%- set child_attr = {
                     'hx-trigger': attr['hx-trigger'],
                     'hx-post': attr['hx-post'],
+                    'hx-target': attr['hx-target']|default('#main-content'),
                     'hx-swap': attr['hx-swap']
                 } -%}
             {%- endif -%}