feat: add deploy-static-site action, site-lib, images; remove deploy-oci-site
Content now served from S3 at runtime via shared static-server image.
- deploy-static-site: reads creds from Nomad vars, builds site, pushes
tarball to S3, generates per-domain Nomad job JSON, deploys
- generate-job.py: emits Nomad job JSON for a static site deployment
- site-lib/flake.nix: mkSite helper, packages.default + devShells only
- images/flake.nix: shared static-server OCI image (sws + awscli2 + tools)
- images CI: builds and pushes static-server on images/flake.nix changes
- deploy-oci-site: removed (superseded by deploy-static-site)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>