Docker + Fly.io seed-node config for ZL1

ZL1 seed-node deploy lands. Dockerfile is a tiny multi-stage Rust build; fly.toml declares 1 GB memory + persistent volume for the chain database + restart policy on-failure.

Three Fly gotchas I keep tripping over: (1) min_machines_running = 1 is not the default, and seed nodes need it on; (2) auto_stop_machines = false for the same reason — Fly’s eager scale-to-zero will kill your peer; (3) volumes are region-pinned. If you scale to a new region, you get a new volume, and your chain state isn’t there. Always pin the deploy region.