1D ridge regression (stability): umbrella import

The core real-analysis theorem lives in:

• NN.MLTheory.LearningTheory.Stability.RidgeRegression1D.Real

We keep this short umbrella module so downstream code can simply:

import NN.MLTheory.LearningTheory.Stability.RidgeRegression1D

without needing to remember the internal file split.

The executable float32 development is separate (to avoid pulling in float semantics unless needed):

• NN.MLTheory.LearningTheory.Stability.RidgeRegression1D.IEEE32Exec.