feat(examples): RAS Crew did:trail PoC registry + resolver

[chrishooooo-netizen]

Summary

First production-style reference for did:trail v1: 1 org + 5 agent DID Documents for the Rocking.AI.Sales AI Sales Crew, signed with an ed25519 test key (POC-KEY-NOT-FOR-PRODUCTION).

• Registry (`examples/ras-crew-registry.json`): 6 DID Documents, each with required `TrailRegistryService` endpoint per spec section 3.3.1, trail-hash per section 4.5.2, Ed25519Signature2020 over canonical JSON.
• Builder (`examples/js/ras-crew-poc/build-registry.js`): deterministic, zero-dep.
• Verify-page generator (`examples/js/ras-crew-poc/build-verify-pages.js`): static HTML for trailprotocol.org/verify/ras-crew/.
• Resolver (`examples/js/resolve-ras-crew.js`): verifies registry signature + trail-hash, `--list` and `--test` modes (positive + negative). Test result: 9 passed, 0 failed.

Context

• Builds on feat(spec): Trust Anchor Model (§3.4) + Revocation Propagation (§8.7) - closes #1 #13 (Trust Anchor Model).
• Demonstrates the spec live in a real deployment.
• Answers the W3C CCG thread (Apr 2026) on what an agent identity layer looks like in practice.

Test plan

• `node examples/js/resolve-ras-crew.js --test` → 9/9 pass
• All 6 DID Documents include `TrailRegistryService` endpoint (section 3.3.1)
• trail-hash verified against spec section 4.5.2
• Tampered registry rejected
• Verify pages deployed to trailprotocol.org/verify/ras-crew/

Co-Architect: @AmeyParle