- PtySession.close and _discard_active_session_file: waive the deliberate
teardown catch-alls with reviewed '# health: allow' comments (BLE001+S110).
- pty_ws was over its main-pinned CC cap: extract the channel-marker prologue
into _pty_channel_marker_state and the keep-alive writer loop into
_pump_keepalive_input.
- Map sinh3543@gmail.com -> sinh2024 (check-attribution, PR #133936).