Add structured validation failures

internal/validation/validation.go

@@ -3,7 +3,6 @@ package validation
 
 import (
 	"context"
-	"fmt"
 	"io"
 
 	"gitea.maximumdirect.net/eric/ReleaseKit/internal/gotool"
@@ -25,9 +24,12 @@ type Request struct {
 func Run(ctx context.Context, request Request) error {
 	tool, err := gotool.New(ctx, request.RepositoryDir)
 	if err != nil {
-		return fmt.Errorf("prepare Go toolchain: %w", err)
+		return &Failure{Check: GoTest, Cause: err}
 	}
 	_, err = tool.Run(ctx, request.RepositoryDir, gotool.Native, gotool.Target{}, request.Output,
 		"test", "-mod=readonly", "-count=1", "./...")
-	return err
+	if err != nil {
+		return &Failure{Check: GoTest, Cause: err}
+	}
+	return nil
 }