QA: Headless Chat (Simple) — CrewAI (Crews)

• Navigate to /demos/headless-simple.
• Verify "Headless Chat (Simple)" heading renders.
• Verify the empty-state message "No messages yet. Say hi!" is shown.
• Type "show a card about cats" and press Enter.
• Verify the user bubble (blue, right-aligned) appears.
• Verify the assistant response appears with a ShowCard rendered tool result.
• Verify Agent is thinking... appears while running.