补充 project release handoff 文档

wasm-port/docs/drift-report.md

@@ -6,6 +6,10 @@ As of the current upstream baseline, no byte-level drift is allowed between
 files listed in `tools/source-manifest.txt` and the matching files under
 `../linuxcnc/`.
 
+The project-level release handoff in `docs/project-release-handoff.md` includes
+this drift report in the final acceptance path alongside source reuse,
+OPFS/session, sim-config coverage, host/runtime boundary, SDK, and UI docs.
+
 The enforced upstream baseline is:
 
 ```text