The insights page kept `CorrelationResult` + `DataSummary` type imports
left over from an earlier refactor, and the slim summaries slice still
referenced `RollupGranularity`, `aggregateWmyBuckets`, and
`RollupBucketRow` after the v1.4.37.2 GROUP BY rewrite folded that work
into the narrow aggregate. Pure deletions — both helpers stay exported
for the test suite that still exercises them.