Logistic regression as an NNModuleSpec

The model spec provides a standalone gradient-descent baseline and prediction helpers. This file adds the NNModuleSpec wrapper (Linear + Sigmoid) for composition and export.

def Spec.logisticRegressionModule {α : Type} [Context α] {p : ℕ} (model : LogisticRegression p 0 α) : ModSpec.NNModuleSpec α (Shape.dim p Shape.scalar) (Shape.dim 1 Shape.scalar)

Logistic regression wrapped as NNModuleSpec (linear + sigmoid).

def Spec.logisticRegressionChain {α : Type} [Context α] {p : ℕ} (model : LogisticRegression p 0 α) : ModSpec.SpecChain α (Shape.dim p Shape.scalar) (Shape.dim 1 Shape.scalar)

SpecChain wrapper for logistic regression (useful for composition).