Auto-retry policy

When ZingBot retries a failed workflow and when it stops.

DRAFT — Skeleton auto-scaffolded from docs/workflow-auto-retry-runbook.md. Review before publishing.

ZingBot auto-retries certain transient failures (network blips, transient XING errors).

Terminal failures (wrong credentials, 2FA blocked) are surfaced to the user instead of retried — see the Workflow Auto-Retry Runbook for the full policy.