Fix frontend locale tests after date-fns changed intl formatting

and also attempt to format dates in locale

frontend/src/locale/Utils.test.tsx

@@ -39,19 +39,19 @@ describe("DateFormatter", () => {
 	it("format date from iso date", () => {
 		const value = "2024-01-01T00:00:00.000Z";
 		const text = formatDateTime(value);
-		expect(text).toBe("Monday, 01/01/2024, 12:00:00 am");
+		expect(text).toBe("1 Jan 2024, 12:00:00 am");
 	});
 
 	it("format date from unix timestamp number", () => {
 		const value = 1762476112;
 		const text = formatDateTime(value);
-		expect(text).toBe("Friday, 07/11/2025, 12:41:52 am");
+		expect(text).toBe("7 Nov 2025, 12:41:52 am");
 	});
 
 	it("format date from unix timestamp string", () => {
 		const value = "1762476112";
 		const text = formatDateTime(value);
-		expect(text).toBe("Friday, 07/11/2025, 12:41:52 am");
+		expect(text).toBe("7 Nov 2025, 12:41:52 am");
 	});
 
 	it("catch bad format from string", () => {

frontend/src/locale/Utils.ts

@@ -1,4 +1,9 @@
-import { fromUnixTime, intlFormat, parseISO } from "date-fns";
+import {
+	fromUnixTime,
+	type IntlFormatFormatOptions,
+	intlFormat,
+	parseISO,
+} from "date-fns";
 
 const isUnixTimestamp = (value: unknown): boolean => {
 	if (typeof value !== "number" && typeof value !== "string") return false;
@@ -20,20 +25,19 @@ const parseDate = (value: string | number): Date | null => {
 	}
 };
 
-const formatDateTime = (value: string | number): string => {
+const formatDateTime = (value: string | number, locale = "en-US"): string => {
 	const d = parseDate(value);
 	if (!d) return `${value}`;
 	try {
-		return intlFormat(d, {
-			weekday: "long",
-			year: "numeric",
-			month: "numeric",
-			day: "numeric",
-			hour: "numeric",
-			minute: "numeric",
-			second: "numeric",
-			hour12: true,
-		});
+		return intlFormat(
+			d,
+			{
+				dateStyle: "medium",
+				timeStyle: "medium",
+				hourCycle: "h12",
+			} as IntlFormatFormatOptions,
+			{ locale },
+		);
 	} catch {
 		return `${value}`;
 	}