Storage/save in steps — Canonical v10

Canonical v10 removes the step-level sink: / save: blocks.

Storage is a pattern:

• use normal tools (postgres/duckdb/gcs/nats/…) to persist data
• return a reference (ResultRef / TempRef) for large payloads
• optionally patch non-secret metadata into ctx/iter via task policy (set_ctx / set_iter)

See also

• Result storage (canonical): documentation/docs/reference/result_storage_canonical_v10.md
• ResultRef / TempRef: documentation/docs/reference/tempref_storage.md
• Scopes (workload/ctx/iter): documentation/docs/reference/variables_v2.md