Add a use case: Payments & settlement

[Innovate-With-Sanjeev]

The task

Add a Payments & settlement use case — a curated, learner-first slice of FIBO for a real financial task, plus a grounding context pack. Spec-driven, no code: add one JSON file under curation/usecases/ and the tooling resolves and gates every id.

Why

Payments is one of the most common places teams want a grounded AI agent (settlement instructions, payment obligations, clearing). It exercises FIBO's FBC and FND domains and complements the existing loan / KYC / securities / reg-reporting / derivatives use cases.

Where to start

• Guide: https://github.com/AI-First-Community/kuber-map/wiki/Use-Case-Authoring
• Use an existing spec in curation/usecases/ as a template.
• Anchor concepts live under FBC and FND — verify each IRI against fibo-source/; do not invent classes.

Done when

• curation/usecases/payments.json added; every id resolves to a real FIBO IRI.
• make curate && make map && make pack regenerate cleanly; make check green.
• Cross-domain links carry a rationale + citation and are tagged curated.