Subjective test design planner

A dependency-light Python script (standard library only) that sizes a subjective test DESIGN. From your number of sources (SRC), conditions (HRC), clip length, vote time, and fatigue-limited session length, it computes the full-factorial PVS count (SRC*HRC), the total voting time, the training and stabilizing-clip overhead, and the number of fatigue-limited sessions required; it flags when the design exceeds one session and suggests splitting; and it prints a ready-to-fill ITU-T P.910 §14 report