Add Authentication Best-Practice Guidelines to the onX Standard

[joshfischer-cin7]

onX currently defines message structure and semantics but does not provide guidance on how implementers should authenticate onX message senders and receivers.

While onX should remain authentication-method agnostic, the standard should include non-normative authentication guidelines to help implementers avoid insecure or inconsistent designs—particularly as onX is used to transmit high-impact commands via MCP and LLM-driven workflows.

This task proposes adding an Authentication Guidelines section to the onX standard that:

• Does not mandate a specific authentication mechanism
• Clearly communicates that authentication is required for production use
• Points implementers toward industry-accepted best practices

The goal is to:

• Set a security baseline
• Reduce accidental insecure implementations
• Improve enterprise trust and adoption
• Avoid premature standardization of auth protocols