NormAV1 — research-grade AV1 encoder driven by NormMAP commutator-norm ROI

Prerequisites (install separately):
  - SvtAv1EncApp (e.g., apt install svt-av1, or build from github.com/AOMediaCodec/SVT-AV1)
  - ffmpeg
  Both must be in PATH.

Usage:
  ./slimecodec-svtav1-norm input.mp4 -o output.mp4

Options:
  --qp-range  20 (mild) / 30 (default, ~-20%) / 40 / 60 (most aggressive ~-38%)
  --crf       SVT-AV1 quality target, default 32
  --preset    SVT-AV1 speed (0=slowest/best..13=fastest), default 8

This is a research preview. Empirical (Sparks 9-min, 1080p):
  qpr=30 → -19.9% size at VMAF 94.09 vs plain libsvtav1 baseline (95.29)

Note on FFmpeg's libsvtav1 wrapper:
  This pipeline uses SvtAv1EncApp directly because FFmpeg's libsvtav1
  wrapper does not expose ROI side data. NormMAP analysis is computed
  in this binary, then SvtAv1EncApp is invoked with --roi-map-file.
