s3tables: Improve bucket name validation error message

Replace misleading character-only error message with generic 'invalid bucket
name'. The isValidBucketName() function checks multiple constraints beyond
character set (length, reserved prefixes/suffixes, start/end rules), so a
specific character message is inaccurate.

weed/s3api/s3tables/handler_bucket_create.go

@@ -38,10 +38,10 @@ func (h *S3TablesHandler) handleCreateTableBucket(w http.ResponseWriter, r *http
 		return fmt.Errorf("invalid bucket name length")
 	}
 
-	// Validate bucket name characters [a-z0-9-]
+	// Validate bucket name
 	if !isValidBucketName(req.Name) {
-		h.writeError(w, http.StatusBadRequest, ErrCodeInvalidRequest, "bucket name must contain only lowercase letters, numbers, and hyphens")
-		return fmt.Errorf("invalid bucket name characters")
+		h.writeError(w, http.StatusBadRequest, ErrCodeInvalidRequest, "invalid bucket name")
+		return fmt.Errorf("invalid bucket name")
 	}
 
 	bucketPath := getTableBucketPath(req.Name)