Pin PROMETHEUS AgentPlane SR schema snapshot

[mdheller]

Summary

Pins Prophet Platform PROMETHEUS validation to the AgentPlane symbolic-regression schema snapshot.

This adds local schema snapshots and a no-network validator so platform CI can detect schema drift without live cross-repo fetches.

Changes

• Add local AgentPlane SRRunArtifact schema snapshot.
• Add local AgentPlane SRCandidateRef schema snapshot.
• Add schema-pin validator.
• Add schema-pin documentation.
• Add focused workflow that runs the local PROMETHEUS demo and validates generated run artifacts against the pinned AgentPlane contract shape.

Boundary

AgentPlane remains the schema owner. These files are local validation snapshots only.

Acceptance criteria

• Pinned schema snapshot hashes validate locally.
• Generated PROMETHEUS local-demo run artifacts include AgentPlane-required fields.
• Method families remain inside the AgentPlane enum.
• SINDy controlAuthority remains false.
• Candidate references preserve required fields and promotion boundaries.