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/stocks/ui/StocksPage/StocksPage.view.tsx

@@ -18,6 +18,7 @@ import { LoadingSkeleton } from "@wealthledger/ui";
 import { useTranslation } from "react-i18next";
 import { Link } from "react-router";
 
+import { ApiErrorCode, isApiErrorCode } from "@/shared/api";
 import { formatMoney, formatSnapshotTime } from "@/shared/lib";
 
 import type { StocksPageVm } from "./StocksPage.vm";
@@ -156,8 +157,8 @@ const StocksPageView: FC<StocksPageViewProps> = (props) => {
 					<Stack gap="xs">
 						<Text>
 							{t(
-								vm.code === "TBANK_NOT_CONNECTED"
-								|| vm.code === "INVALID_TBANK_TOKEN"
+								isApiErrorCode(vm.code, ApiErrorCode.TbankNotConnected)
+								|| isApiErrorCode(vm.code, ApiErrorCode.InvalidTbankToken)
 									? "stock.connect"
 									: "stock.sectionError",
 							)}