test(client): verify async lifecycle equivalence

crates/irtt-client/src/lib.rs

@@ -3,6 +3,8 @@
 //! `irtt-client` opens IRTT-compatible sessions, sends echo probes, receives
 //! replies, classifies loss/late/duplicate packets, and emits [`ClientEvent`]
 //! values for callers to consume directly or aggregate with `irtt-stats`.
+//! With the `tokio` feature enabled, `AsyncClient` provides the same low-level
+//! lifecycle for callers that own a Tokio runtime and drive readiness directly.
 //!
 //! Timing values intentionally preserve signed measurement semantics. When
 //! server timing is available, [`RttSample::effective`] is adjusted for server