Function build_queue_wait_timeout_frame 

pub fn build_queue_wait_timeout_frame(
    correlation_id: u64,
    stream_id: u16,
    queue: &str,
    wait_ms: u64,
) -> Result<Frame, BuildError>

Build a QueueWaitTimeout frame for an elapsed wait (issue #919).

A distinct frame kind — not a QueueEventPush (which always carries a delivered message) and not a StreamError (reserved for parse failures, cancellation, and runtime errors) — so the client can tell “your wait budget elapsed with nothing deliverable” apart from a delivery and apart from a cancellation purely from the frame kind. Echoes the open’s correlation_id + stream_id so the client pairs the timeout with the wait it opened; the small JSON body restates the queue and the budget that elapsed for client-side logging.