viable/strict/1788211462: Refactor scaled matmul meta validation (#195408)

发生了什么

Human Note Small reactor to enable the later commits Agent note This extracts the common scaled-matmul shape and recipe validation from the structured meta implementation without changing its contract. The following stack commit reuses this boundary for scaled addmm. Authored with assistance from an AI coding assistant. Test Plan bash ~ /.ptq_workspace/scripts/rebuild.sh ~ /.ptq_workspace/jobs/20260829-pytorch-adhoc…

摘要按规则整理自下方来源原文

来源