docs: per-dataset snapshot settings and delegation behavior in the cluster-sidecar guide; reranker, schema evolution, and refresh processed metrics (#2472) * docs: per-dataset snapshot settings and delegation behavior in the cluster-sidecar guide; reranker, schema evolution, and refresh processed metrics * docs: say that the zero-results fallback skips the sidecar's refresh_sql filter --------- Co-authored-by: Emma Spice <emma@EmmasMacStudio.localdomain>