Save Agent Workflow

Attach an imported workflow to an agent and mark the agent's provider CUSTOM.

This is the persistence step for document-ingested workflows (e.g. an IVR diagram parsed in Bluejay AI): the reviewed graph becomes the agent's stored workflow with no external source behind it.

Only agents with no workflow provider (or already CUSTOM) accept an import — an agent synced from ElevenLabs/VAPI/Retell/DFCX is refused with 409 so an import can never clobber a provider-managed workflow.