onAsanaTaskChanged matches all task changed events, including completion changes.
automations/watch-asana-task-changes.automation.ts
resourceId is required. Optional static account defaults to the project binding.
Returns an event signal with action: "changed", resourceType: "task", task reference, and optional field-level change. The payload is compact; fetch the task for its complete current state. Completed events also match On Asana task completed.