Pulse Curation Layer & UI — Three Layers per Category, Triage Per Item, Finalize on Demand

Pulse-shaped bundles (Entity Pulse and its siblings) produce multi-item structured rollups that the human triages item-by-item. The data model needs three layers per category — an immutable `raw_output` from the LLM fan-out (audit trail), a live `curated_output` that updates as the user accepts to canonical, accepts to additional context, or discards each item, and an immutable `finalized_output` snapshot taken when the user marks the triage done. Re-firing a bundle later creates new raw + curated layers; the previous finalized is sticky. This spec codifies the three-layer pattern, the triage actions, the row schema, and the UI shape — the layer the Response Reviewer (per Decision §10) renders for pulse-shaped responses.