Remove LetterOfCredit (fold into FinanceAgreement), add favicons
Summary
Small ontology refinement plus a favicon for both published sites.
Ontology
- Remove the LetterOfCredit class and its issuingBank / creditAmount properties. A letter of credit is a FinanceAgreement with financeType "letter of credit" (its issuing bank is the financier, its credit amount is the financeAmount), so the class duplicated FinanceAgreement. All four terms were UNSCRO-authored (no BSP/UNTP origin), so no source fidelity or mapping depends on them.
- Re-home beneficiary to TradeAgreement (beneficiary → Party), alongside buyer and seller. It was the one LoC property without a FinanceAgreement equivalent, and it matches the existing cl:beneficiary party-role concept.
Result: 89 classes, 743 properties, all eight validation gates pass. Finance now has Account, FinanceAgreement, Insurance, Payment and PaymentMeans.
Tooling
- Fix build-migration-ledger.py: it was preserving a UNSCRO-authored new term as "kept" even after the term was removed from the graph. It now drops such rows, so the ledger reflects the live ontology (the four removed terms are gone, beneficiary returns as a survivor).
Favicons
- Add the UN logo favicon to both sites: app/favicon.ico for the Nextra docs site (GitLab Pages), and site/favicon.ico copied into dist/ with a head for the resolvable vocabulary. Verified served on both (/favicon.ico and /vocabulary/favicon.ico).