shep-channel 0.7.2

Client for the shep shepherd channel: readiness, metrics and custom actions over the descriptor shep hands a supervised process
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# shep-channel

Speak the shep shepherd channel from a supervised app: signal readiness,
emit a metric, answer an action.

```rust
let shepherd = shep_channel::serve();
let (stop, wait_for_stop) = std::sync::mpsc::channel();

shepherd.on_action("gc", |params, _name| {
    format!("collected, params={params:?}")
});
shepherd.on_shutdown(move || {
    let _ = stop.send(());
});
shepherd.ready()?;
shepherd.metric("rps", 4200.0);

// Serve until the shepherd asks this app to stop.
wait_for_stop.recv().ok();
```

Ask for a channel in the Flockfile with `channel = true`, or get one from
`wait_ready` or `shutdown_with_message`.

Without one, every call above does nothing and the app runs unchanged, so
there is nothing to branch on. An action name you did not register still
gets a reply, which is the part an app is most likely to get wrong: to the
shepherd, silence from an app thinking hard and silence from an app that
never understood the question look the same, and only `action_timeout`
running out tells them apart.

The wire itself is documented in `docs/shepherd-channel.md` in the shep
repository. It is language agnostic, and Go, JavaScript and Python
libraries over the same contract are planned.

shep is pre-release. Anything public here can change before 1.0.

## License

MIT OR Apache-2.0, at your option.