cmux ssh --command hop can stall on host-key prompt

When working around a remote session lock by running cmux ssh <owner-node> --command 'ssh <other-node>', the inner ssh runs on the first node, whose known_hosts may lack the target even if your laptop trusts it. It then waits at a yes/no prompt, while the workspace can still list as [ssh:connected]. Check with ps on the node and who on the target rather than trusting the status; a read-screen that returns blank means you cannot see the prompt. In one session cmux send returned OK but the answer never registered, so seed known_hosts on the hop node first, after comparing ssh-keyscan's fingerprint with the laptop's entry. Separately, the session name for managed SSH is derived from the app bundle tag, so every node sharing an NFS home contends for one lock.