feat(auth): add remembered local login to the frontend

frontend/src/api/pi-management.ts

@@ -1,4 +1,4 @@
-import { ApiError, apiFetch } from "./client";
+import { ApiError, apiErrorMessage, apiFetch } from "./client";
 
 export type PiReasoning = "low" | "medium" | "high";
 
@@ -54,22 +54,14 @@ const errorCodes = new Set<PiManagementApiErrorCode>([
   "pi_management_write_failed",
 ]);
 
-function object(value: unknown): Record<string, unknown> | undefined {
-  return value && typeof value === "object" && !Array.isArray(value)
-    ? value as Record<string, unknown>
-    : undefined;
-}
-
-/** Narrows the sanctioned error payload without ever surfacing its raw response body. */
+/** Narrows the sanctioned error code and derives its message locally. */
 export function asPiManagementApiError(error: unknown): PiManagementApiError | undefined {
   if (!(error instanceof ApiError)) return undefined;
-  const payload = object(error.payload);
-  const code = payload?.code;
-  const message = payload?.error;
-  if (typeof code !== "string" || !errorCodes.has(code as PiManagementApiErrorCode) || typeof message !== "string") {
+  const code = error.code;
+  if (typeof code !== "string" || !errorCodes.has(code as PiManagementApiErrorCode)) {
     return undefined;
   }
-  return { status: error.status, code: code as PiManagementApiErrorCode, message };
+  return { status: error.status, code: code as PiManagementApiErrorCode, message: apiErrorMessage(error) };
 }
 
 export const getPiManagementStatus = () => apiFetch<PiManagementStatus>("/pi-management/status");