Add Node mxc_ffi library loader

[Branden Bonaby (bbonaby)]

📖 Description

Adds the Node SDK's cross-platform mxc_ffi library resolver and Koffi loader. It searches explicit overrides, packaged native assets, and local Cargo outputs, then binds mxc_version as a loader smoke test.

🔗 References

• [Proposal] Unify one-shot SDKs on typed requests #1137

🔍 Validation

• npm run build
• node --test dist/tests/unit/native-library.test.js

✅ Checklist

• Signed the Contributor License Agreement
• Linked to an issue
• Updated documentation (if applicable)
• Updated Copilot instructions (if build, architecture, or conventions changed)
• If this PR changes Cargo.lock, the dependency-feed-check check passes (see docs/pull-requests.md)

📋 Issue Type

• Bug fix
• Feature
• Task

Microsoft Reviewers: Open in CodeFlow

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[Branden Bonaby (bbonaby)]

Closing at the author's request; the branch is being kept for review and no code was merged.