The VPS runs Caddy inside Docker as part of the Hephaestus stack (not
system-wide angie as the earlier deploy/README assumed), so the shape
of the deploy is: Prometheus runs as its own small docker-compose that
attaches to Hephaestus's existing network, and Hephaestus's Caddy
reverse-proxies prometheus.x → prometheus:3700.
Dockerfile: node:22-alpine base (keeps the image ~55 MB and gives us
node:sqlite stable), tini for signal handling, non-root `node` user,
one /data volume holding the DB + ed25519 service key + uploads +
snapshot build output.
docker-compose: one service, attaches hephaestus_default as external
network, env sourced from an .env file alongside the compose. The .env
is NOT committed (contains ADMIN_PUBLISHER, optional VirusTotal key,
optional payment config). Healthcheck polls /healthz.
The deploy/prometheus-service.service systemd unit from the earlier
commit is now unused on this host (kept for anyone deploying natively
on a non-dockered box).
