fix(azure): savings plan inventory uses the ARM resource name as ResourceType, so the duplicate guard likely never matches #492

Problem

The Azure savings plan duplicate guard probably never matches in production, so a recently bought savings plan does not suppress the matching recommendation.

convertSavingsPlan (providers/azure/services/savingsplans/client.go:247-248 on main) sets the inventory commitment's resource type from the ARM resource name:

if sp.Name != nil {
    commitment.ResourceType = *sp.Name
}

The recommendation side sets the literal "Compute" (benefit_recommendations.go:239). recfilter.DuplicateChecker keys both on ResourceType|Region|engine|deployment, so a commitment matches a recommendation only if sp.Name == "Compute".

For an ARM resource, name is the last segment of its ID: /providers/Microsoft.BillingBenefits/savingsPlanOrders/{orderId}/savingsPlans/{savingsPlanId}. In the SDK's own examples (armbillingbenefits@v1.0.0, savingsplan_client_example_test.go) that ID is GUID-shaped (for example 20000000-0000-0000-0000-000000000000). The plan type is carried in sku.name ("Compute_Savings_Plan", line 150), and convertSavingsPlan never reads it.

Every test fixture sets "name": "Compute" (e.g. scope_test.go), which is why the tests pass.

Impact

If real list responses carry a GUID name, these are all inert in production:

• dedupe of owned plans;
• the billing-account single-scope attribution from fix(azure): attribute single-scope savings plans billed to a billing account #468;
• the cross-subscription covering list proposed in fix(azure): count savings plans billed to another subscription in the duplicate check #491.

A savings plan bought within the lookback window would not suppress a repeat recommendation, so the same commitment could be bought twice.

Not verified live

This is inferred from ARM naming rules and the SDK examples. No live Azure call was made. Please confirm against one real SavingsPlanClient.NewListAllPager response before fixing.

Suggested fix

Derive the resource type from sku.name, mapping Compute_Savings_Plan to Compute, and fail loud on an unknown SKU. Do not use name. Add a fixture with a GUID name and a sku.name, run through the real DuplicateChecker.

Found while reviewing #491 (review by claude-go-pr-merge-4). The problem predates that PR.