Preserve expected ARM error classification

Keep the original ARM error when hosted key retrieval fails so authorization failures retain their classification through the outer configuration boundary.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 68ccefda-9e7d-4b01-a4db-e390810491ee

src/hooks/useKnockoutExplorer.ts

@@ -456,7 +456,7 @@ async function configureHostedWithAAD(config: AAD): Promise<Explorer> {
     if (userContext.features.enableAadDataPlane) {
       console.warn(e);
     } else {
-      throw new Error(`List keys failed: ${e.message}`);
+      throw e;
     }
   }
   updateUserContext({