fix: Prevent translation loading spinner from showing on page load

The CSS rule `display: flex` was overriding the `hidden` attribute on
the loading indicator element. Changed to use `:not([hidden])` selector
so the flex layout only applies when the element is not hidden.

Author: chrisns

cloudformation/scenarios/localgov-drupal/drupal/web/modules/custom/ndx_aws_ai/css/content-translation.css

@@ -60,15 +60,19 @@
 }
 
 .translation-widget__loading {
-  display: flex;
-  align-items: center;
-  gap: 10px;
   margin-top: 15px;
   padding: 10px;
   background: #fff;
   border: 1px solid #b1b4b6;
 }
 
+/* Only show as flex when not hidden - display: flex would override [hidden] attribute */
+.translation-widget__loading:not([hidden]) {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+}
+
 .translation-loading-spinner {
   display: inline-block;
   width: 20px;