asana.addTaskComment posts one comment and can pin it atop the task activity.
automations/comment-on-asana-task.automation.ts
taskId and exactly one of non-empty text or htmlText. The htmlText value must use Asana-supported rich-text HTML. Optional isPinned controls pinning, and second argument { account } defaults to the project binding.
Returns the created AsanaStory. Keep its id to update or delete it.