prepare_authority_steering_selection.py had no callers and its --out-dir default pointed
at a June run dir; the validator's --n-per-source does its job now.
export_authority_steering_selection.py is axis-agnostic via --axis-filter despite the
name, as docs/20260705_persona_library_user_perspective.md papercut 3 noted. Renamed.
Co-Authored-By: Claudypoo <288921227+claudypoo@users.noreply.github.com>
