Refine S3 Tables implementation to address code review feedback

- Standardize namespace representation to []string
- Improve listing logic with pagination and StartFromFileName
- Enhance error handling with sentinel errors and robust checks
- Add JSON encoding error logging
- Fix CI workflow to use gofmt -l
- Standardize timestamps in directory creation
- Validate single-level namespaces

weed/s3api/s3tables/utils.go

@@ -5,6 +5,7 @@ import (
 	"path"
 	"path/filepath"
 	"regexp"
+	"strings"
 	"time"
 )
 
@@ -98,3 +99,26 @@ func splitPath(path string) (dir, name string) {
 	name = filepath.Base(path)
 	return
 }
+
+// validateNamespace validates that the namespace provided is supported (single-level)
+func validateNamespace(namespace []string) (string, error) {
+	if len(namespace) == 0 {
+		return "", fmt.Errorf("namespace is required")
+	}
+	if len(namespace) > 1 {
+		return "", fmt.Errorf("multi-level namespaces are not supported")
+	}
+	name := namespace[0]
+	if len(name) < 1 || len(name) > 255 {
+		return "", fmt.Errorf("namespace name must be between 1 and 255 characters")
+	}
+	return name, nil
+}
+
+// flattenNamespace joins namespace elements into a single string (using dots as per AWS S3 Tables)
+func flattenNamespace(namespace []string) string {
+	if len(namespace) == 0 {
+		return ""
+	}
+	return strings.Join(namespace, ".")
+}