DEV: a real selection change has a pointerup event (#1427)

This is needed for discourse/discourse#33143 as we now rely on this pointerup event.

Author: jjaffeux

spec/system/ai_helper/ai_post_helper_spec.rb

@@ -39,7 +39,8 @@ def select_post_text(selected_post)
       "var element = document.querySelector('#{topic_page.post_by_number_selector(selected_post.post_number)} .cooked p'); " +
         "var range = document.createRange(); " + "range.selectNodeContents(element); " +
         "var selection = window.getSelection(); " + "selection.removeAllRanges(); " +
-        "selection.addRange(range);",
+        "selection.addRange(range);" + "const event = new PointerEvent('pointerup');" +
+        "document.dispatchEvent(event);",
     )
   end