Tensor summaries provide deterministic bounded statistics for traces and policies.
Use PartialSummary for mergeable streaming statistics. Entropy and quantiles require raw distributions or scalar token-level aggregates.
alias CrucibleSignal.TensorSummary
left = TensorSummary.from_list([1, 2])
right = TensorSummary.from_list([3, 4])
{:ok, merged} = TensorSummary.merge(left, right)
merged.mean