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/shared/api/problem-details.ts

@@ -1,7 +1,30 @@
+enum ApiErrorCode {
+	BankDependentRefunds = "BANK_DEPENDENT_REFUNDS",
+	BankIntentConflict = "BANK_INTENT_CONFLICT",
+	BankNotFound = "BANK_NOT_FOUND",
+	BankRefundLimit = "BANK_REFUND_LIMIT",
+	BankVersionConflict = "BANK_VERSION_CONFLICT",
+	BankWriteConflict = "BANK_WRITE_CONFLICT",
+	BondTickerAmbiguous = "BOND_TICKER_AMBIGUOUS",
+	Forbidden = "FORBIDDEN",
+	InvalidOperationsCursor = "INVALID_OPERATIONS_CURSOR",
+	InvalidTbankToken = "INVALID_TBANK_TOKEN",
+	NotFound = "NOT_FOUND",
+	StockTickerAmbiguous = "STOCK_TICKER_AMBIGUOUS",
+	TbankNotConnected = "TBANK_NOT_CONNECTED",
+	TbankUnavailable = "TBANK_UNAVAILABLE",
+	Unauthorized = "UNAUTHORIZED",
+}
+
 function apiErrorCode(error: unknown): string | undefined {
 	return typeof error === "object" && error !== null && "code" in error
 		? String(error.code)
 		: undefined;
 }
 
-export { apiErrorCode };
+// Incoming codes are an open wire string; unknown values retain their fallback.
+function isApiErrorCode(value: unknown, expected: ApiErrorCode): boolean {
+	return value === expected;
+}
+
+export { ApiErrorCode, apiErrorCode, isApiErrorCode };