previewuse

Provision the AWS resources and CI secrets that previewuse needs — S3 bucket, EC2 key pair, security group, IAM instance profile, GitHub/CircleCI OIDC role, and the CI secrets that wire it all together. Use when the user asks to "provision preview AWS", "set up the AWS prerequisites for previewuse", "create the IAM roles for preview deploys", "finish the previewuse setup", or runs /provision-preview-aws. Usually invoked after `configure-preview-deploy` has filled in `preview.config.sh`. Confirms each AWS action before running it and writes GitHub secrets via `gh secret set` when authed.

Wire previewuse (per-branch preview environments on EC2) into the current repo. Use when the user asks to "set up preview deploys", "configure previewuse", "add preview environments", "deploy previews per branch", or runs /configure-preview-deploy. Discovers compose services, fills in preview.config.sh, generates Caddyfile + CI workflow, and explains the AWS prerequisites that still need to be set up by hand.