Causal Transformer Models

Canonical public import for TorchLean's GPT-style causal Transformer support.

NN.API.Models.CausalTransformer.Architecture owns configuration, shape families, and graph construction. NN.API.Models.CausalTransformer.Runtime owns indexed-token and tied-weight execution programs and causal-language-model objectives.

Import this module for the complete API, including one-hot and bounded-token models with either an independent vocabulary head or a projection tied to the token-embedding table. Tokenization and checkpoint formats remain in their respective API modules.