How do I set up a human-in-the-loop approval step in a durable agent workflow with Catalyst?

In Catalyst, use Dapr Workflow's WaitForExternalEvent method to pause the workflow until a human sends an approval event. First, define a workflow step that awaits an event with a specific name and optional timeout. Then, have an external system—like a web UI or approval service—send that event via Dapr's API. The workflow resumes from the pause point, preserving all state. This pattern works for any agent framework.