支持delete，修改err输出为stderr

cmd/saastool/task.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"fmt"
-	"log/slog"
+	"os"
 	"strings"
 )
 
@@ -29,7 +29,8 @@ func RunTask(args ...string) error {
 		return RunTaskRun(args...)
 	default:
 		err := fmt.Errorf(`unknown command "%s"`+"\n"+`Run 'saastool task help' for usage`, name)
-		slog.Warn(err.Error())
+		fmt.Fprintln(os.Stderr, err)
+
 		return err
 	}
 }