## Why
Doctor's rollout statistics only counted `.jsonl` files, omitting storage used by compressed `.jsonl.zst` rollouts.
## What changed
Recognize compressed rollouts when collecting active and archived file counts, total bytes, and average bytes. Count both physical files when plain and compressed representations coexist, while continuing to ignore unrelated files and compression temporary files.
## Testing
Extend the rollout statistics test to cover nested plain and compressed files, coexisting representations, archived compressed rollouts, and ignored files, with a snapshot of the reported counts and sizes.
GitOrigin-RevId: 46197f9741884668b50fb6a1d0a07060020f12ed