feat(contract-appeals): add the contract appeals resource

[makegov-mark]

What

Adds the contract_appeals resource, new in Tango API 4.26.0: Contract Disputes Act appeal decisions from the Civilian Board of Contract Appeals (CBCA, 2007–present) and the Armed Services Board of Contract Appeals (ASBCA, 2010–present). These are disputes under an existing award, not bid protests — those stay on listProtests.

client.listContractAppeals(options?: ListContractAppealsOptions): Promise<PaginatedResponse<...>>
client.getContractAppeal(uuid: string, options?: { shape?, flat?, flatLists?, joiner? }): Promise<ContractAppealRecord>

• ListContractAppealsOptions extends the shared list options and names all ten filters: search, board, docket, appellant, judge, decision_type, decision_date_after / _before, listed, document_id, plus ordering.
• ContractAppealRecord types the 21 response fields, all optional: an unshaped list response carries only a core subset, so an unrequested field is absent rather than null. decision_text is Enterprise-gated and absent below that tier.
• CONTRACT_APPEAL_SCHEMA is registered as the ContractAppeal model, and both conformance scripts learn the resource → method / model mapping.
• Response fields keep the repo's snake_case convention (docket_numbers), matching ProtestRecord; camelCase stays for method and option names.

Testing

Gate	Result
npx vitest run	430 passed across 47 files, 34 new
npm run typecheck	clean
npm run lint	clean
npm run check-conformance	no errors, only pre-existing warnings
npm run check-shape-coverage	0 new gaps
npm run build	clean

New tests cover list with filters, listed: false surviving rather than being dropped, no synthesized shape, explicit shape passthrough, retrieve by uuid, empty-uuid rejection before any request, and decision_text present vs. absent-not-null.

Notes

• Unit tests rather than a cassette. The integration suite replays recorded cassettes and a missing one is a hard failure; recording needs a live call. This mirrors tests/unit/client.sled.test.ts, the repo's other full-resource unit suite. A cassette can be recorded in a later refresh.
• No shape preset. Presets are pinned to tango-python by a parity test, so inventing one here before Python picks its field list would create drift — and listProtests does not send its preset either.
• Uses the generic list path, like listProtests. The shaped path validates against the local schema and would reject a caller's shape client-side for a resource whose shape tree is not in the vendored contract yet. The schema is still registered so the coverage gate has a model at the next re-vendor.
• The two script mappings are inert today — the vendored contract is API 4.25.1 and has no contract_appeals — and exist so the next re-vendor does not hard-fail on an unmapped resource.
• npm run format is unsafe here: it rewrites ~35 unrelated files. It was reverted; only the 10 files above are touched. Two of them already fail prettier --check at HEAD, before this change, and were left alone rather than smuggling a whole-file reformat into this diff.
• No version bump — the release flow bumps at release time and the contributor guide asks only for an ## [Unreleased] entry.

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