ssh-keyscan was being called with set -e in effect and stderr suppressed,
so a single keyscan failure killed the entire deploy with no diagnostic
output. Since rsync/ssh use StrictHostKeyChecking=no, the known_hosts
entry is not load-bearing — making the keyscan best-effort is safe.
stderr is now captured to /tmp/keyscan.err and emitted as a warning so
future failures are debuggable.
Agent-Session: cowork-deploy-fix-20260414
c5f4149698