feat(insurance): per-recommendation Archera quotes (blocked on an Archera API mapping) #799

Goal

Show Archera insured-commitment figures per platform recommendation, as a per-rec or ladder view, instead of only the plan-wide comparison delivered by platform#785.

Blocked: needs an Archera API capability that is not documented

The documented comparison (GET /v1/org/{org_id}/commitment-plans/{plan_id}/comparison, consumed through pkg/insurance) returns:

• plan-wide hypothetical rollups per (contract term, payment option); and
• per-line rows keyed by Archera line_item_id.

There is no documented key linking an Archera line item to a platform recommendation (provider account, region, resource type, commitment), and no endpoint that quotes an arbitrary recommendation. pkg/insurance therefore documents the comparison as plan-wide and the plan ID as "an Archera plan identifier, not a local recommendation ID" (types.go:193-194). Any per-rec mapping invented locally would show figures for the wrong commitment.

What would unblock it

One of these, documented by Archera:

• a line-item field that identifies the underlying cloud resource or commitment in terms we can match exactly;
• a quote endpoint that accepts our recommendation parameters; or
• a written mapping rule from Archera.

Scope once unblocked

• Contract change in go pkg/insurance (decode the new field or endpoint, with tests from official samples).
• Platform UI: per-recommendation insured columns, or a ladder view by term, behind the same default-off config.
• Mapping must be exact. An unmatched recommendation shows "no Archera quote", never an estimate.

Acceptance criteria

• An Archera documentation source for the mapping is cited in the go PR.
• Exact-match tests, including the unmatched and ambiguous cases, which must fail loud.
• Same disclosures and not-a-guarantee caveat as platform#785.

Dependencies

Requires vendor documentation (owner to raise with Archera), the real-scenario verification issue, and platform#785 merged. Tracking: #786.