docs(changelog): add the pkg/insurance Archera comparison contract

[cristim]

Closes #311

Adds one ### Added entry under [Unreleased] in CHANGELOG.md for pkg/insurance (#285). Docs only; every statement is taken from the package doc in pkg/insurance/types.go, eligibility.go, client.go and the merged #285 body. It says no live Archera call has been made.

Not folded: #286 is code and test follow-ups (sanitizer, Retry-After boundary, %p), so it stays separate. No overlap with this entry beyond the documented %p caveat.

markdownlint CHANGELOG.md passes.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Added details on the read-only Archera insured-commitment comparison client, including its API endpoints and constraints.
  • Clarified how monetary values and nullable fields are represented, which products are supported, and how sensitive keys are redacted.
  • Documented that verification is performed offline only.

[coderabbitai]

Important

Review skipped

Review was skipped as selected files did not have any reviewable changes.

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• CHANGELOG.md

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📝 Walkthrough

Walkthrough

The Unreleased changelog now documents the read-only Archera insured-commitment comparison client, its API constraints, response semantics, supported-product results, key redaction behavior, and offline-only verification.

Changes

Archera contract documentation

Layer / File(s)	Summary
Document the client contract CHANGELOG.md	The Unreleased entry describes the client’s API endpoints and constraints, money and nullable-field semantics, supported-product results, key redaction behavior, and offline-only verification.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~3 minutes

Change: Other

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Merge Risk: ⚪ Minimal · up to f5efe

No actionable issue remains in the changelog entry; it is ready to merge after normal checks.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: adding the pkg/insurance Archera comparison contract to the changelog.
Linked Issues check		The diff adds one ### Added entry under [Unreleased] in CHANGELOG.md. It documents the read-only pkg/insurance client and decoders, the two Archera endpoints, fixed origin, x-api-key authent…
Out of Scope Changes check		The whole-PR diff contains only the requested CHANGELOG.md documentation entry. The added details describe the pkg/insurance contract and its documented limitations. No unrelated code, tests, or p…
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…

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[cristim]

Gate verdict: CLEAN at e08c81c.

Every CHANGELOG claim checked against code at this SHA (not the PR body): premium inside commitment_cost.total with no recompute helper (types.go package doc); 730 h monthly vs separate one-time upfront (Financials/Totals); Currency always nil, no expiry, FetchedAt only (types.go Comparison, quote.go:347); nullable ContractTerm/PaymentOption/CommitmentType (types.go); ComparisonRow keeps Current plus all Candidates (quote.go:289-310); 100% target is a requested target (types.go doc); AssessProductSupport supported only for aws/AmazonEC2 and aws/savingsplan/Compute, else unknown (eligibility.go); fixed BaseURL, x-api-key only, redirects blocked via ErrUseLastResponse and 3xx becomes HTTPError, single-shot GET with no retry (client.go); %p/%T redaction caveat (client.go Config/Client Format docs); no importer of pkg/insurance outside the package; no live call (PR #285 body "What is not proven").

Local evidence (git archive of this SHA, GOTOOLCHAIN=go1.26.9, GOWORK=off): go test ./insurance exit 0, 103 passed. markdownlint CHANGELOG.md: clean. No em-dashes in the diff, no secrets. Branch is ahead 1, behind 0 of main. CI 15/15 pass, mergeStateStatus checked before merge.

[cristim]

Gate update: main moved after the verdict above; mergeStateStatus is now BEHIND at e08c81c. Not merged. Author: merge main (normal merge, no force); the CHANGELOG-only verdict carries if the merge adds nothing else, then re-gate.

[cristim]

Gate evidence at f5efeef: CHANGELOG.md byte-identical to the content-reviewed e08c81c (verdict CLEAN there); markdownlint clean; go test ./insurance ok (GOTOOLCHAIN=go1.26.9, git archive of this SHA); CI 15/15 pass. Not merged: main moved again and mergeStateStatus is BEHIND; the one allowed update-branch is spent, so the coordinator must decide how to proceed (merge window or another update).

[cristim]

Gate evidence at 945ed7c: CHANGELOG.md byte-identical to content-reviewed e08c81c (verdict CLEAN); markdownlint clean; go test ./insurance ok (git archive, go1.26.9); CI 15/15 pass; mergeStateStatus CLEAN. Merging with --match-head-commit.