The custom launch_gemv_bf16 kernel produces NaN when output dimension N is small (e.g. N=32 for the MoE router). Fall back to cuBLAS GemmEx for N < 256. Also removes the padding workaround in gpt_oss MoE forward. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>