Short-circuit `queue_async_op` for Poll::Ready

Editor assessment

Excellent perf message shape. The subject names the exact function, queue_async_op, and the exact condition, Poll::Ready, so readers know precisely where the short-circuit applies without opening the diff; the runtime scope is correct and the line is short and imperative. This is how performance commits should identify their targets. What is missing is evidence: no body, no microbenchmark numbers, no note on how much overhead the Ready path previously paid through the async op queue. For a hot-path optimization in the core runtime, a few measured figures would justify the change during review and make the entry credible in release notes.