fix: replace debug fmt.Println with hlog in printNode

Problem

\printNode()\ function in \engine.go\ uses \mt.Println\ and \mt.Printf\ for debug output, which writes directly to stdout instead of using hertz's logging framework (\hlog).

Impact

• Debug output bypasses the logging system configuration
• Cannot control log level or output destination for these messages
• Inconsistent with the rest of the codebase which uses \hlog.SystemLogger()\

Fix

Replace \mt.Println/\mt.Printf\ calls with \hlog.SystemLogger().Debugf()\ to integrate with hertz's logging framework.

Local environment limitations, relying on CI/CD automated testing.