Run FER validation at Z=128 with normalized min-sum (alpha=0.875).
Best alpha found via sweep: 0.875 (threshold 2.90 photons/slot).
Z=128 matrix achieves girth=8 vs girth=6 at Z=32.
Add Z=128 vs Z=32 FER comparison plot.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
