Generate a title + description from a workflow's steps (one aux call,
reused for step labels) whenever it is still auto_named, so a workflow
built in the Edit Agent names itself on commit instead of staying
"New workflow". A manual rename sets auto_named=False and is never
overwritten. Stream the aux call (non-streaming drops content on some
9router lanes) and fall back to a step-derived title when the model is
unavailable.