QC report builder (layered, honest, stakeholder-ready)

A dependency-free (pure standard-library) Python tool that turns per-frame quality scores into a LAYERED, stakeholder-ready QC report — the article's thesis made runnable. It does NOT decode video or compute VMAF; it consumes scores you already measured and applies the four trust habits: (1) REPORTS THE WORST FRAMES — pools arithmetic mean, harmonic mean, median, 10th/5th/1st percentile, and the minimum, so the report shows a central number AND a floor; (2) SHOWS UNCERTAINTY — prints a 95% inter