Writes one settled conflict, replacing the entity's previous one.
The conflict kept for one entity, or null when none was archived for it.
Every conflict of one layer, via the composed key — no secondary index needed.
Every conflict, across every layer, in key order.
Drops one entity's conflict — a no-op when it holds none.
Drops one layer's conflicts, or all of them when layerId is omitted.
OptionallayerId: string
Public API of the conflicts store.