Get Insights List Batch

Shared listing parameters plus the entities to fan out over.

Mirrors get_insights_list's query parameters exactly, because that is the function this delegates to -- one entity at a time, unchanged. Keeping the names identical is what makes the delegation auditable.

entities is capped because every element runs the whole get_insights_list path -- Neo4j, Postgres and search -- and the route fans them out concurrently. Uncapped, one request is a way to hold as many connections of those shared pools as the caller cares to ask for.