Add Legal Core v0.1 policy kernel fixtures

[mdheller]

Summary

Adds the first SCOPE-D Legal Core v0.1 tranche for governed evidence work.

This creates:

• config/schemas/legal-core.schema.json
• docs/legal-core-v0.1.md
• tests/fixtures/legal-core/defensive-endpoint-triage.allowed.json
• tests/fixtures/legal-core/unknown-authority.blocked.json

Why

The Finder / QuickLook / WebKit preview-surface case showed that endpoint evidence, document triage, semantic promotion, runtime action, graph binding, and report emission need legal/policy gates at the core.

This PR makes the first Legal Core contract explicit:

• authority basis is required;
• unknown authority blocks collection, runtime action, semantic promotion, graph binding, and report emission;
• unsafe rendering and credential access are blocked by schema;
• claim states are bounded to observed / inferred / hypothesis / forecast / excluded / unresolved;
• non-claims are mandatory.

Validation

Static JSON schema/fixture tranche only in this PR.

Manual structural checks performed:

• branch is ahead of main by 4 commits;
• added schema and fixtures are JSON documents;
• allowed and blocked fixtures both include non-claims;
• blocked fixture explicitly denies collection, runtime action, semantic promotion, graph binding, and report emission.

Non-goals

• Does not provide jurisdiction-specific legal advice.
• Does not certify production readiness.
• Does not confirm compromise or clear compromise.
• Does not make source availability equivalent to permitted use.

Related

• Reference architecture rollout: canonical governed-intelligence contract sociosphere#310
• Legal Core runtime gate for AgentPlane action admission and receipts agentplane#266