feat: add CI/CD pipeline and Nomad deployment for tailnet-only hosting
Dockerfile: multi-stage Node 22 build + Caddy static file server
Caddyfile: MPA routing for all 7 editor entry points + immutable asset caching
Nomad job: Tailscale sidecar on big-nix → atmosphere-docs.lobster-hake.ts.net
Gitea Actions: test → build → deploy → verify pipeline
service.json: tailnet service contract metadata
Requires Nomad host volume and variable setup before first deploy.