Tags matching `vX.Y.Z-*` (e.g. v3.4.0-rc1, v1.0.0-beta.2) are treated as
internal/staging builds. They skip the tag-vs-manifest check because
pre-releases do not flow to end users via `/plugin update`, which reads
the manifest on the default branch.
Stable tags `vX.Y.Z` still require all five version sources to match
exactly, so the protection against the #874 drift remains intact. The
cross-file consistency check on PRs is unchanged — all manifests must
still agree with mempalace/version.py whenever any version file moves.