Common utilities for MPC-node services.

This crate provides building blocks shared across nodes in the MPC network.

• Environment – represents the deployment environment (prod / staging / test).
• StartedServices – tracks whether all async background services have started, used to drive the /health endpoint.
• spawn_shutdown_task / default_shutdown_signal – wiring for graceful shutdown via CTRL+C or SIGTERM.
• version_info! – macro that returns a version string containing the crate name, semver version, and git hash.

Optional Features

• api (enabled by default) – exposes /health and /version Axum endpoints.
• serde (enabled by default) – ser/de implementation for Environment.
• aws (enabled by default) – adds a method to create a localstack configuration used for testing