webui: Fix branching logic on edit message (#21175)

* fix: Branching logic + small refactor

* chore: update webui build output

tools/server/webui/src/lib/utils/index.ts

@@ -22,6 +22,7 @@ export { default as autoResizeTextarea } from './autoresize-textarea';
 // Branching utilities
 export {
 	filterByLeafNodeId,
+	findMessageById,
 	findLeafNode,
 	findDescendantMessages,
 	getMessageSiblings,