4 arms x 7 runs vs real DrussGT. mix alternates the two guns 476 times/7 runs
(liveness OK) but our bullets are no more varied (power sd / aim-offset sd flat)
and DrussGT's dodge quality is unchanged (miss/tick mix-pat +0.03, p=0.66; MDE
3.8%). mix wins 24/49 = the 49% baseline; the user's 6/10 has P=0.353 at 49%.
New tools/ab/ab_dodge_analyze.py splits the validated per-shot dodge instrument
by arm and adds gun-switch/power/bearing liveness; fixtures committed.
SirStone
32a5e72fac