docs: record cursor theme checkout source

frontend/README.md

@@ -92,7 +92,10 @@ frontend/src/
   dependency is currently declared as
   `file:../../../Engines/engines/teamhub-cursor-theme` in `frontend/package.json`;
   the current source package version is `0.1.0` from the Engines package
-  manifest, and the consumer is not yet pinned to a release tag.
+  manifest; the audited Engines checkout during the 2026-06-21 consumer
+  remediation is `5beb82b30cd2e7baa52c61aa1d21e684428ca737`; the consumer is
+  not yet pinned to a release tag. Verification: `npm run build` passed on
+  2026-06-21.
 
 ### Key flows