fly-io-deployment

Use when making a service deployable to Fly.io, writing or reviewing a fly.toml, or building the deploy pipeline. Every fly.toml field annotated, the four service shapes (HTTP service, database, frontend, one-shot job), 6PN .internal and .flycast networking, scale-to-zero and when not to, volumes and state, configuration and secrets, the tag-driven pipeline with change detection, bootstrapping a new app, scaling and teardown, and cost.