FROST PHASE 7 — AUTHORITY BAND SIMPLIFICATION

From the same repository layout with immutable prior frost releases:
  OPENBLAS_NUM_THREADS=1 OMP_NUM_THREADS=1 python scripts/build-frost-phase7.py --stage select
  OPENBLAS_NUM_THREADS=1 OMP_NUM_THREADS=1 python scripts/build-frost-phase7.py --stage assess
  OPENBLAS_NUM_THREADS=1 python tests/frost-phase7.test.py

Select loads only 2021–2023 outcome rows. Assess checks the frozen checkpoint
before loading 2024. Neither stage models 2025. The zip contains code, tests,
phase 7 evidence and model engines, not duplicated prior source releases.
A-bands are authority bands. D-band LSOA mileage validation remains open.
Review design.json for nested folds, equivalence, calibration and limitations.
