nx_breast_localize.nx

nx_breast_localize.nx -- find left/right breast sub-regions in torso. In real renders the two breasts are connected to torso as one CC, so we can't isolate them by connected-component alone. The substrate splits the upper-third of the torso at midline and computes the bounding box of skin-mask pixels in each half. Outputs per-breast bbox + centroid + area_px. Output flat-array (packed): result[0..4] left breast: x0, y0, x1, y1, area_px result[5..9] right breast: x0, y0, x1, y1, area_px result[10] left centroid_x result[11] left centroid_y result[12] right centroid_x result[13] right centroid_y