Records the manual update process (module moved -> build -> reconcile; and the
breaking-change freeze/re-register recovery), and the two things that make
self-update more than a webhook: the build-on-push trigger is currently HAL's
(hal-gitea-tools on :9877), a retirement gap the mesh must replace with its own
forge-webhook trigger wired to every repo including mesh-controller; and the
builder validates manifests too, so a breaking change couples controller +
builder + manifests + hosts, and renaming the builder's own seat deadlocks its
rebuild. Names the transition discipline (accept old+new for one release) that
self-update needs so a push does not auto-freeze.