Adds AimingAtTheSternHitsTheStern, ThinLimbCostsHitChance, PlacementAndProbabilityShareOneKernel and EveryHitLandsOnMetal per the spec's Verification block. Each test builds its own synthetic hull/catalog fixture. The aim marker in every fixture is authored with very high durability so it survives the whole sample of shots without dropping out of the reveal ranking partway through.
