ROWCOL-04 localization: RT rows regression (18.0 vs 10.6 pre-rework) is
CONTENT BIAS, zero in the sky and +10..22 counts in terrain rows - with
dense high-contrast content nearly every |UM residual| exceeds max_abs,
all pixels get the outlier weight and the weighted mean degenerates to
the row's content mean (the small weights cancel), stamping bias bands.
lineAverage now zeroes a line's correction when its inlier fraction is
below rowcol_min_inlier (default 0.33 - content-dominated lines cannot
yield a line-noise measurement) or when |estimate| > max_abs (line noise
cannot physically exceed the gate scale). Both guards are no-ops with
the gate off (max_abs INF - every pixel is an inlier).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>