Go 1.27.1 in go.mod and in the Dockerfile's test and build images.
Every module go.mod requires is at its current release; protoc-gen-go
follows protobuf to v1.36.12 and mf.pb.go is regenerated. The new
standard library uuid package replaces github.com/google/uuid; the
FromBytes call could only fail on a length validateUUID already checks,
so it and its unreachable error are gone. make vulncheck runs
govulncheck v1.8.0, installed with go install at its release commit, in
a vulncheck stage of the Dockerfile on the digest-pinned golang image;
script/check does not run it. A new test pins the bytes of a seeded
manifest written by an mfer built before this change.
Model: opus-5-5
