fix optional project auditor dependencies

[Daliys]

Normal contributor PRs must target development. main is release-only and accepts only maintainer release PRs from development or release/*.

Summary

Validation

• Package compiles in Unity.
• Relevant Editor tests pass.
• NexusQualityGate passes or remaining warnings are intentional.
• Public/protected C# types and methods have useful XML documentation.
• Python bridge still compiles (python3 -m py_compile Editor/nexus_unity_bridge.py Editor/nexus_bridge/*.py).
• Public docs updated for behavior/API changes.
• CHANGELOG.md updated for public changes.

Safety checklist

• Server remains loopback/local-only.
• File operations remain constrained to the Unity project root.
• No generated caches, Python bytecode, .DS_Store, Unity Library/, or local agent artifacts included.
• No secrets, credentials, private project source, or proprietary assets included.