data(emotion): cross-model GT drift report — opus vs sonnet on 534 (#93)

A second model (Sonnet) independently labeled all 534 tracks; emotion_drift.py
measures where it disagrees with the opus GT. Result:
  mean V/A drift     0.322
  quadrant agreement 72%
  emotion Jaccard    0.53
  174 uncertain-GT tracks (top-quartile drift or quadrant mismatch)

The disagreements aren't noise — they CONCENTRATE on genres that straddle the
circumplex, which is a real finding:
  - hardstyle (The Prophet, Headhunterz): triumphant/euphoric (+,+) vs
    aggressive/tense (-,+) — the genre's 'euphoric aggression' lives on the
    quadrant line.
  - uplifting trance (Cosmic Gate, Ferry Corsten, Markus Schulz): euphoric vs
    driving/tense — same boundary.
  - neoclassical (Nils Frahm, Ólafur Arnalds, Max Richter): calm-positive vs
    melancholic-calm.

So ~33% of the corpus carries genuinely uncertain emotional GT, and it's
predictable WHICH third. Those tracks should be down-weighted (not trusted) in
the upcoming scale calibration — single-model GT would have hidden this.