Add a use case: Insurance underwriting

[Innovate-With-Sanjeev]

The task

Add an Insurance underwriting use case — a curated FIBO slice for assessing and pricing risk on a policy, plus its grounding context pack. Spec-driven, no code: one JSON file under curation/usecases/.

Why

Insurance is a large, underserved domain for grounded agents (policies, insured risks, premiums, claims). FIBO has dedicated coverage this use case would make teachable and agent-ready.

Where to start

• Guide: https://github.com/AI-First-Community/kuber-map/wiki/Use-Case-Authoring
• Template: an existing spec in curation/usecases/.
• Read the IRIs from fibo-source/, never from memory.

Done when

• curation/usecases/insurance-underwriting.json added; all ids resolve.
• make curate && make map && make pack regenerate cleanly; make check green.
• Cross-domain links have a rationale + citation, tagged curated.