The deploy job now validates DEPLOY_HOST, DEPLOY_USER, DEPLOY_KEY, and
DEPLOY_PATH secrets before attempting SSH operations. This replaces the
cryptic ssh-keyscan failure with a clear error message explaining which
secrets need to be configured.
Also made ssh-keyscan more robust by quoting the hostname and adding
fallback handling.
Ref: YM-CD-DEBUG-20260310-001
Co-authored-by: qinfendebingshuo <207279273+qinfendebingshuo@users.noreply.github.com>
copilot-swe-agent[bot]