quantal-ternary: the third state is real — thresholded ternary, 2.1469, and a stranger who counted the zeros

A third-party audit asked if a 2-bit model ever wants a zero. We measured 34% of the weights do, rebuilt the quantizer as a true thresholded ternary, retrained to 2.1469 masked val, and hit our tightest Rust parity yet — 1.3e-5. The story of the night the format finally earned its third code.