Adds a Supervisor layer to pkg/process that manages long-running
processes and goroutines with automatic restart, panic recovery,
and graceful shutdown. Supports both external processes (DaemonSpec)
and Go functions (GoSpec) with configurable restart policies.
Also exposes AddHealthCheck on the Daemon struct so supervised
services can wire their status into the daemon health endpoint.
Co-Authored-By: Virgil <virgil@lethean.io>
