- Replaced `statistics.mean`, `statistics.stdev`, and `statistics.pvariance` with pure-Python builtins using `sum()` and `len()`.
- Added performance optimization logging to `.jules/bolt.md`.
- Updated tests and verified results match the original.
Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: aguzererler <6199053+aguzererler@users.noreply.github.com>