Main configuration d=256, L=64: all data, figures and checks re-run

Every OMA reference takes the L/16 combining gain so the comparison
stays resource matched, four hardcoded copies of the configuration are
replaced by MAIN_D or the main curve, and stage_J's K-by-L Gaussian
draw becomes its exact scalar Beta equivalent.

data/sec_jam.csv

@@ -1,8 +1,8 @@
 jsr_db,blind,matched,nojam
--10,0.41313,0.602758,0.257308
--5,0.583948,0.79449,0.257308
-0,0.772444,0.917424,0.257308
-5,0.902872,0.97136,0.257308
-10,0.964788,0.990494,0.257308
-15,0.988114,0.99704,0.257308
-20,0.99617,0.999024,0.257308
+-10,0.100512,0.370894,0.053384
+-5,0.186312,0.629542,0.053384
+0,0.364964,0.838068,0.053384
+5,0.610574,0.94122,0.053384
+10,0.816206,0.980862,0.053384
+15,0.929192,0.993638,0.053384
+20,0.97542,0.997986,0.053384