Deploy frontend React app as S3 static site and serve via CloudFront

Currently, the frontend is run as a separate React app. To improve this setup and better demonstrate fullstack serverless deployment, we want the frontend to be built and deployed to an S3 bucket, served as a static site, and then distributed via CloudFront.

Requested Changes:

• Update the sample app's infrastructure to include:
  • Building the React frontend for production.
  • Deploying the frontend build artifacts to an S3 bucket configured for static site hosting.
  • Creating a CloudFront distribution to serve the S3 static site frontend.
  • Ensure the Terraform configuration accommodates these changes and automates the deployment as part of the sample app's overall infra.
• Update documentation to describe the new deployment flow for the frontend.

These changes will make the sample app more realistic and provide a complete serverless stack example.