Fused stages

Stage	Description
LorenzoQuantStage	Fused float predictor + quantizer (1-D/2-D/3-D)
DifferenceStage (negabinary-fused)	First-order difference with inline negabinary encoding (DifferenceStage<T, TOut> where TOut != T)

‍Note: DifferenceStage with a TOut != T template argument fuses a negabinary encoding step into the differencing kernel (equivalent to DifferenceStage<T> followed by NegabinaryStage, but in a single pass). This stage lives in modules/predictors/diff/, not in modules/fused/, but is listed here so all fused-operation options appear in one place.