refactor: enforce enum machine codes #18

Use owner enums for known codes; preserve wire values and unknown fallbacks.

Verified npm ci and verify: 379 tests, 5 lint checks, app and Storybook builds.

src/pages/stock/ui/StockPage/StockPage.tsx

@@ -5,6 +5,8 @@ import { LoadingSkeleton } from "@wealthledger/ui";
 import { useTranslation } from "react-i18next";
 import { Link, Navigate } from "react-router";
 
+import { ApiErrorCode, isApiErrorCode } from "@/shared/api";
+
 import { StockPageView } from "./StockPage.view";
 import { useStockPageVm } from "./StockPage.vm";
 
@@ -22,15 +24,15 @@ const StockPage: FC = () => {
 				</Stack>
 			</LoadingSkeleton>
 		);
-	const unavailableMessage = vm.code === "STOCK_TICKER_AMBIGUOUS" ? "stock.ambiguousTicker" : "stock.unavailableText";
+	const unavailableMessage = isApiErrorCode(vm.code, ApiErrorCode.StockTickerAmbiguous) ? "stock.ambiguousTicker" : "stock.unavailableText";
 	if (!vm.stock)
 		return (
 			<Stack role="alert">
 				<Title order={1}>{t("stock.unavailable")}</Title>
 				<Text>
 					{t(
-						vm.code === "TBANK_NOT_CONNECTED"
-						|| vm.code === "INVALID_TBANK_TOKEN"
+						isApiErrorCode(vm.code, ApiErrorCode.TbankNotConnected)
+						|| isApiErrorCode(vm.code, ApiErrorCode.InvalidTbankToken)
 							? "stock.connect"
 							: unavailableMessage,
 					)}