quantal-ternary: four nights of training, three dead GPUs, and the format that finally earned its third bit

The full engineering history of the quantal nightly runs — from 11.34 masked val through a thresholded-ternary rewrite, a GPU that died mid-epoch, a stranger who counted zeros in the published bytes, and the 1.3e-5 parity gate that finally made training equal deployment. Every number, every crash, every fix.