Schema to validate the input attributes of a completed run.

The worker may send either:

• final_dataclip_id — reuse an existing step output dataclip (single leaf)
• final_state — leaf state to persist as a dataclip (multiple leaves). Map values are stored as-is. Non-map values (numbers, strings, booleans, lists) are wrapped as %{"value" => x} before persistence.

These are mutually exclusive. If both are sent, final_dataclip_id wins.