Returns the environment provenance for an execution run — the layers it used,
split into the software-environment dimension (python-env / r-env layers) and the
inputs / reference-data dimension (data layers). Each layer's identity
(layerType, snapshotId, treeChecksum, pythonVersion) was frozen onto the run at
creation.
Historical: compute-node layers were retired, so only runs from before then
report any layers; newer runs return empty lists. Runs older than the frozen
identity report their layers by name only.
For org-scoped compute nodes, the caller must be a member of the associated
organization. For user-scoped compute nodes, only the owner can access.