A2A + Kafka

### Is your feature request related to a problem? Please describe.

Hello! Would be nice to have a demo about how to set up A2A with Kafka using A2A Python SDK. Could something like that be part of this samples repository? Thank you very much

### Describe the solution you'd like

Inspired this blog about ["Why Google’s Agent2Agent Protocol Needs Apache Kafka"](https://www.confluent.io/blog/google-agent2agent-protocol-needs-kafka/)

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct