Smoke test Agent Network with A2A request

The HR-IT Onboarding Network is now deployed. Help me test it by generating a sample A2A request payload to the broker that covers this scenario: "A new employee with ID E003 is starting. Look up their info, find an available laptop, and assign it to them." Show me the raw JSON request body I should POST to the broker's /tasks/send endpoint, and the expected artifact structure in the response.