Wire the config loader, backends, and HTTP server into an executable.
`serve` runs the resolve hop until SIGINT/SIGTERM (graceful shutdown);
`get` resolves one ref to stdout as a bare value with no trailing
newline for $(...) exec-style plumbing. Exit codes: 0 ok, 1 usage or
config error, 2 resolution failure.
💘 Generated with Crush
Assisted-by: Crush:glm-5.2
