10-task TDD plan covering workflow/ types package, 8 service files,
WorkflowEventStream, sealed Event interface, DeleteBatchJob, version
bump, and changelog update.
Design spec for integrating Mistral Python SDK v2.2.0 changes into the
Go SDK v1.2.0. Covers Workflows API (37 methods across 8 sub-resources),
DeleteBatchJob addition, sealed event interface with 17 variants, and
SSE streaming with StreamPayload envelope.
