ethernet8023: the seeded E2E (turn.start -> deltas -> turn.end with history_version/
message_count) was cut to hello+bogus-frame while ComputeHost._run_real_turn stays live.
New suite drives server._sessions + _run_prompt_submit through the host: turn.started,
message.delta rpc frames, turn.end identity (history_version=1, message_count=2), sid-
required/session-busy turn.error, stale queued-generation -> interrupted, live interrupt
frame ack + interrupted turn.end, and the explicit-stop compat matrix ported off HostSession.
c447b9c80c