Add knowledge and intelligence adapter scaffolds

[mdheller]

Summary

Adds dependency-free adapter scaffolds for the SourceOS knowledge and intelligence planes.

This PR implements the first tested boundary for issue #6 without claiming live service integration yet.

It adds:

• knowledge.py with shared knowledge artifact/result primitives.
• Slash Topics adapter for topic scope selection and policy-gated membrane application.
• Memory Mesh adapter for policy-gated recall and writeback.
• New Hope adapter for semantic-thread normalization and policy-gated claim extraction.
• Sherlock Search adapter for policy-gated search packet creation and context hydration.
• Holmes adapter for request/status/artifact correlation only, preserving the Holmes boundary.
• MeshRush adapter for policy-gated graph view and graph artifact events.
• In-memory test backends for all six planes.
• Tests proving policy gates, artifact references, context metadata, and Holmes correlation-only behavior.

Boundary decisions

• AgentTerm records governed requests and artifact/status references.
• AgentTerm does not own Slash Topics, Memory Mesh, New Hope, Sherlock Search, Holmes, or MeshRush semantics.
• Holmes remains request/status/artifact correlation only; this PR does not redefine Holmes behavior.
• Sensitive retrieval, memory, search, investigation, claim extraction, graph, and membrane operations require Policy Fabric decision references.
• Workroom, topic, Matrix, agent, policy, and artifact metadata are preserved for downstream evidence.

Validation

Expected CI:

ruff check .
pytest

Part of #6.