Add Open Publication Resolver (OPR) register for third-party attestation discoverability
Introduces a fifth UNTP register catalogueing resolver services operated by parties other than the subject of attestation. Closes the protocol gap that today prevents civil-society monitors, multi-stakeholder mechanisms, regulators, and other independent parties from making their attestations about supply-chain subjects discoverable without subject cooperation.
Anchored in OECD Due Diligence Guidance for Responsible Supply Chains of Minerals from Conflict-Affected and High-Risk Areas (Step 1(E), Step 3(B)(2)(b)(i), Step 4(B)(2), Gold Supplement Step 5 footnote 59). Cross-sector applicability to ESPR/EUDR/UFLPA/IUU monitoring.
- New register: registers/opr/{register-schema,register}.json (entries: [])
- New sample: artefacts/samples/v0.7.0/opr/OpenPublicationRegister_instance.json
- New section in IdentityResolver.md: Implementation Guidance: Third-Party Open Publication Resolvers
- New docs at website/docs/implementations/opr/: index, governance, registration-guide
- New generator at .claude/scripts/generate-opr-register-md.js
No schema changes to existing UNTP credential types. No new normative MUSTs. No real entries (operators self-submit per registration-guide.md once their resolver is operational and verifiable).