Integrate the simpleaichat in a webapp using Pluto

[jianzs]

@minimaxir Hi Max! I noticed two items on the simpleaichat roadmap that I'd like to contribute to:

1. An example of integrating simpleaichat into a web application
2. A demonstration of using simpleaichat in a stateless context, such as with AWS Lambda functions

I've developed a web backend sample that combines simpleaichat with my project, Pluto (https://github.com/pluto-lang/pluto). Pluto simplifies cloud application development by providing a streamlined programming interface for leveraging cloud features and building business logic.

The sample can be deployed on AWS with a single command: pluto deploy. I've created a PR (pluto-lang/pluto#227) and a video (https://asciinema.org/a/660515) that demonstrates the deployment and testing process.

I believe this sample effectively showcases the integration of simpleaichat and Pluto, and I hope it serves as a valuable resource for the community.

Please let me know if you have any questions or feedback.