[codex] Rewrite @bsv/did as SD-JWT VC compatibility layer

[sirdeggen]

Summary

• Add new package @bsv/did with SD-JWT VC issuer/holder/verifier flows built on existing @bsv/sdk primitives.
• Add optional secp256k1 did:key support, DID document generation, and QR code generation modes (did and vc).
• Implement selective disclosure using salted SD-JWT disclosures and Key Binding JWT flow.
• Add tests, TypeScript build config, and docs entries for package index/reference.

Validation

• ./node_modules/.bin/tsc -b && ./node_modules/.bin/tsconfig-to-dual-package tsconfig.cjs.json
• ./node_modules/.bin/jest --passWithNoTests
• ./node_modules/.bin/ts-standard src/**/*.ts tests/**/*.ts
• node scripts/validate-frontmatter.mjs && node scripts/check-links.mjs

Notes

• This is scoped as a draft by default.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[sonarqubecloud]

Quality Gate failed

Failed conditions
1 Security Hotspot
0.0% Coverage on New Code (required ≥ 80%)
D Reliability Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

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