Add TriTRPC policy/evidence AUX profile and example verification

[mdheller]

Summary

This draft PR publishes the additive policy/evidence AUX scaffolding for TriTRPC:

• docs/policy_evidence_aux_profile.md
• fixtures/policy_evidence_aux_examples.json
• spec/drafts/tritrpc_policy_evidence_aux_profile.md
• tools/verify_policy_evidence_aux_shape.py

Why

TriTRPC already has an AUX field and deterministic framing/receipt expectations. This PR defines a draft carriage profile for policy/evidence references so integrations can carry:

• grant refs
• policy decision refs
• semantic proof refs
• HDT decision refs
• attestation refs

without changing the stable v1 wire layout.

Scope note

This draft PR intentionally lands the additive files first. The follow-on commit on this same branch should wire the small in-place repo updates:

• README pointer
• repository guide pointer
• integration readiness checklist pointer
• Makefile aux-shape target
• repo copy of spec note in spec/README-full-spec.md

Validation intent

The included verifier is a repository-local shape/canonical-string gate for the published example set. Full cross-language AUX-bearing frame vectors remain a follow-on step.

[mdheller]

Dependency note / merge order:

This transport-facing AUX profile PR should be merged after:

1. socioprophet-standards-storage#61
2. mcp-a2a-zero-trust#3

Reason:

• #61 publishes the normative identity/governance contracts.
• #3 stages the runtime evidence reference substrate that this AUX carriage profile is intended to carry.

Recommended merge position:
3. TriTRPC#37

agentplane#27 should follow this, because runtime evidence/replay should consume the published governance context and transport carriage expectations.

[mdheller]

@copilot resolve the merge conflicts in this pull request and fix the checks

[Copilot]

@copilot resolve the merge conflicts in this pull request and fix the checks

Resolved. The only conflict was an add/add in spec/drafts/tritrpc_policy_evidence_aux_profile.md — both sides had identical content but different line wrapping; adopted main's formatting. All checks pass (make verify: rust-fmt, go-fmt, rust-test, go-test, fixtures). Merge commit: 316cde8.