Function kill_gracefully 

pub async fn kill_gracefully(
    child: &mut Child,
    grace_period: Duration,
    server_name: &str,
) -> KillOutcome

Kill a child process gracefully: send SIGTERM, wait for the grace period, then send SIGKILL if still alive.

On non-Unix platforms (Windows), falls back to child.kill() immediately since SIGTERM is not well-defined.

Arguments

• child - The child process to kill.
• grace_period - How long to wait after SIGTERM before sending SIGKILL.
• server_name - Name of the server (for logging).

Returns

The KillOutcome indicating whether the process exited gracefully or had to be killed.