Add Prophet evidence.v1 lane schemas and fixture vectors

[mdheller]

Summary

Add the first Prophet constitutional service lane to TriTRPC as transport/fixture material, not as a semantic redefinition.

Lane: evidence.v1

Methods:

• SubmitEvidence.REQ / SubmitEvidence.RES
• VerifyEvidence.REQ / VerifyEvidence.RES
• PromoteEvidence.REQ / PromoteEvidence.RES

Proposed file placement

spec/salad/prophet/evidence/v1/
  fair_object.avsc
  provenance_record.avsc
  authority_scope.avsc
  policy_context.avsc
  EvidenceSubmitRequest.avsc
  EvidenceSubmitResponse.avsc
  EvidenceVerifyRequest.avsc
  EvidenceVerifyResponse.avsc
  EvidencePromoteRequest.avsc
  EvidencePromoteResponse.avsc

fixtures/
  vectors_hex_prophet_lane1.txt
  vectors_hex_prophet_lane1.txt.nonces

docs/prophet/
  evidence_lane1.md

Boundary rule

TriTRPC should carry the typed payloads and fixtures. It should not redefine the canonical semantics of evidence, authority, policy, promotion, or provenance. Those semantics should remain sourced from standards/ontology documents.

Acceptance criteria

• Schemas are added under spec/salad/prophet/evidence/v1/.
• Fixture vectors and paired nonces are added under fixtures/.
• Documentation explains service/method naming, schema/context IDs, and stable v1 assumptions.
• The PR clearly states this is the first Prophet constitutional service family.