fix: use idp variant for resource auth login page icons

The resource auth login page (auth/resource/[resourceGuid]) loads IdPs via
the global /idp list in the non-saas/non-org path and passed idp.type as the
icon variant. Since type is always 'oidc' for OIDC-backed providers (Google,
Azure), the branded logos were never selected, showing the generic OIDC icon
instead.

Use idp.variant (with type as fallback), matching the fix already applied to
the main login page (auth/login) and org login page (auth/org/[orgId]).

Fixes #3631

src/app/auth/resource/[resourceGuid]/page.tsx

@@ -283,7 +283,7 @@ export default async function ResourceAuthPage(props: {
         loginIdps = idpsRes.data.data.idps.map((idp) => ({
             idpId: idp.idpId,
             name: idp.name,
-            variant: idp.type
+            variant: idp.variant ?? idp.type
         })) as LoginFormIDP[];
     }