I updated the SM version check logic in py_executor_creator.py to allow MLA chunked prefill and KV cache block reuse on SM121 (Blackwell) architectures. Specifically, I added SM121 (121) to the validation lists for both enable_block_reuse and enable_chunked_context checks, preventing the executor from automatically disabling these features on Blackwell GPUs.

This resolves issue #15344, where these optimization features were being disabled on SM121 devices because the Python-side validator was missing SM121 in its allowlist. The underlying C++ kernels already support SM121, so this change enables full compatibility for MLA optimizations on this hardware.