Add a deploy step to each template's Set up CI page #102

Set up CI covers building and testing but never deploying, and Lambda's page is a copy of Minimal API's.

Phase 1: The guide

• Add a deploy step example per template: push the image to a registry for the four HTTP templates, and deploy through an AWS role with OIDC for Lambda
• Rewrite Lambda's Set up CI page for Lambda

Checks: the site builds, and the workflow snippets pass actionlint.