Follow-up to the salvaged #9560 fix:
- Replace the _TRAVERSAL_RE regex with an explicit _is_path_unsafe() helper
(drops the now-unused `import re`); catches a path separator ANYWHERE,
not just leading, so a non-leading Windows backslash can't slip through.
- Switch the per-entry skip in _ensure_loaded_locked from print() to
logger.warning to match the module's logging conventions.
- Add AUTHOR_MAP entry for the contributor.
- Add regression tests for the non-leading-separator case.
4d4ba0831e