Client layer: bound a request to a deadline.

Runs the downstream call in a monitored child process and returns {error, timeout} if it does not finish within Ms, killing the child (which tears down the in-flight connection). Add it with livery_client:timeout/1.

A {stream, Reader} response body holds a live connection owned by the child. Before the child exits, this layer hands that connection to the caller via the adapter's adopt/2, so the caller's later read/1 does not race the child's death.