- docs: expand and clarify docstrings for SiLU class and its method (mathematical formula, motivation, properties vs ReLU/GELU, usage, and references to Swish/LLM papers)
- test: add unit tests for SiLU (shape/dtype, behavior on large/small values, PyTorch reference, gradients, broadcast)
- no logic/API changes
This update improves reliability and usability of the SiLU activation module.
