docs(#771): hold generic storage migration wrapper

README.md

@@ -157,10 +157,12 @@ mosaic storage status
 mosaic storage tier
 mosaic storage export
 mosaic storage import
-# `mosaic storage migrate --run` is a schema-wrapper compatibility command only;
-# it delegates solely to mosaic-db-migrator and is not tier data copy.
-# Tier data copy is the KBN-101 secure migrate-tier route after activation, with
-# --target-url-file and --target-attestation-file references only.
+# Schema migration is unavailable in this release. The current storage wrapper shells
+# directly to `pnpm --filter @mosaicstack/db db:migrate`; it is legacy N-1,
+# uncertified, and MUST NOT be invoked pending KBN-101-02/-03/-06/-08 activation.
+# Future schema migration is non-operative: external bootstrap → TLS/roles → runner
+# --run → runner --verify → readiness. Tier copy uses only the separately held secure
+# migrate-tier route.
 ```
 
 ### Telemetry