Enable race testing in validation

docs/consumers/publish.md

@@ -8,6 +8,9 @@ result, err := releasekit.Publish(ctx, releasekit.ReleaseRequest{
 	RepositoryDir: "/work/project",
 	Product:       "Example",
 	Version:       "v1.2.3",
+	Validation: releasekit.ValidationSpec{
+		Go: releasekit.GoValidationSpec{Race: true},
+	},
 	AdditionalChecks: func(ctx context.Context, candidate releasekit.Candidate) error {
 		return runProjectChecks(ctx, candidate.RepositoryDir)
 	},
@@ -20,12 +23,15 @@ fmt.Println(result.Version, result.CandidateCommit, result.TagObject)
 
 Publication captures a clean candidate on `main`, validates its committed
 release note, and checks the selected remote before running candidate checks.
-It always runs `go test -mod=readonly -count=1 ./...` with the available
-compatible local Go toolchain. It then calls `AdditionalChecks` once when
-supplied. The standard suite cannot be replaced; move product-specific behavior
-into `AdditionalChecks` and remove repeated standard-suite commands from custom
-checks. A failed suite or additional check prevents tag creation, and wrapped
-errors preserve their causes.
+It runs one `go test -mod=readonly -count=1 ./...` suite with the available
+compatible local Go toolchain. Set `Validation.Go.Race` to run that suite with
+`-race`; its zero value keeps the ordinary native suite. It then calls
+`AdditionalChecks` once when supplied. The standard suite cannot be replaced;
+move product-specific behavior into `AdditionalChecks` and remove repeated
+standard-suite commands from custom checks. A failed suite or additional check
+prevents tag creation, and wrapped errors preserve their causes.
+If race prerequisites are unavailable, the selected suite fails as `go-test`
+instead of silently running without the race detector.
 
 If `Build` selects targets, ReleaseKit verifies them after the standard suite
 and additional checks, before creating the tag. The operation then rechecks the