Raise Go to the latest release, update dependencies, use the standard library uuid, add a vulnerability check (closes #102)

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 standard
library uuid package replaces github.com/google/uuid; FromBytes could
only fail on a length validateUUID already checks, so that call 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; script/check does not run it. The newer go directive
switches on lint checks for strings.SplitSeq and t.Chdir, now used. A
new test pins the bytes of a seeded manifest written by an mfer built
before this change.

Model: opus-5-5

mfer/deserialize_path_test.go

@@ -10,8 +10,8 @@ import (
 	"strings"
 	"testing"
 	"time"
+	"uuid"
 
-	"github.com/google/uuid"
 	"github.com/klauspost/compress/zstd"
 	"github.com/multiformats/go-multihash"
 	"github.com/stretchr/testify/assert"
@@ -92,7 +92,7 @@ func TestDeserializeRejectsInvalidEntryPaths(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			id := uuid.New()
+			id := uuid.NewV4()
 			data := wrapInner(t, id, craftInnerBytes(id, tt.path))
 
 			_, err := NewManifestFromReader(bytes.NewReader(data))
@@ -150,7 +150,7 @@ func TestDeserializeRefusesEntriesThatDecodeTooLarge(t *testing.T) {
 			entry = protowire.AppendTag(entry, 303, protowire.BytesType) // MFFilePath.ctime
 			entry = protowire.AppendBytes(entry, nil)
 
-			id := uuid.New()
+			id := uuid.NewV4()
 			inner := protowire.AppendTag(nil, 102, protowire.BytesType) // MFFile.uuid
 			inner = protowire.AppendBytes(inner, id[:])
 
@@ -181,7 +181,7 @@ func TestDeserializeDropsUnknownFields(t *testing.T) {
 	entry = protowire.AppendString(entry, "a")
 	entry = append(entry, unknown...)
 
-	id := uuid.New()
+	id := uuid.NewV4()
 	inner := protowire.AppendTag(nil, 101, protowire.BytesType) // MFFile.files
 	inner = protowire.AppendBytes(inner, entry)
 	inner = protowire.AppendTag(inner, 102, protowire.BytesType) // MFFile.uuid