PINN PyTorch

Verification-facing PyTorch import surface for trained PINNs.

This module exists so verification call sites can import one file: NN.Verification.PINN.PyTorch.

Implementation is split for readability:

• NN.Verification.PINN.PyTorch.Load parses JSON into a shape-checked PinnState.
• NN.Verification.PINN.PyTorch.ParamStore turns a PinnState into the CROWN graph/parameter representation used by the verifier.