Redesign after the independent-mask dominance finding: the affinity
now parameterizes the receiver (closed-form Wiener) instead of the
mask ensemble. New Theorem 1 (spectral closed form), floors
sqrt(1-b^2)/2 vs 1/2, full-cooperation bound with equality at b=1.
GPU (torch) Monte Carlo backend, decision-directed SIC baseline,
TikZ block diagram source, verification suite V1-V11.
KiHoLee