Interface ElasticSearchHitsResponse<SearchResultItem>

The minimal shape extractSearchResultItems needs - deliberately not the full Elasticsearch response envelope (which also varies per app in its aggregations/total/shards shape). A richer app-specific response type (e.g. one with total, aggregations, extra hit fields like score/index/sort) still satisfies this via TypeScript's structural typing, so no app needs to adopt a shared response type just to use this utility.