CultNetRudpSession::receive records a reliable sequence before reassembly, so
keeping the session after it refuses a frame made the sender's retransmit be
acknowledged and the frame silently lost. The hub and the socket transport now
end that peer's session, send it a Disconnect, and surface the end to the
caller (a Disconnected event, disconnect_reason()). The hub and socket
constructors reject initial_sequence u32::MAX and max_pending_reliable_packets
Some(0), so the accept_connect drops are unreachable. pending_accept_for_resend
becomes public for the document server.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>