Add Nobulex to Governance section

[arian-gogani]

Nobulex - Cryptographic receipts for AI agent actions. Two Ed25519 signatures per action, hash-chained via JCS/RFC 8785. MIT licensed.

• Microsoft merged into Agent Governance Toolkit (PRs #1302, #1333)- 9 independent byte-match validated implementations- ~4,500 npm downloads, OpenSSF Best Practices passing (113%)npm: @nobulex/mcp-server