Mirrors the WS-13 progress semantics onto the axum upgrade path with
three integration tests over the real HttpAdapter surface (also the
COV-11b dark-knob gate — with_ws_idle_timeout had no test caller):
the forever-dribble client is evicted with 1001 despite arriving
messages; a productive session round-trips calls across many windows
without eviction; the None knob never evicts a dribbling client.