report_build.py reads stress_results.json (when --stress-results given),
adds a stress block (cases + by_axis), per-axis scaling-curve PNGs, aggregate
stress headline metrics, and stress regression rows vs the previous run.
Degrades to no stress section when the file is absent.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Martino Ferrari