fix(useFormatDate): default Message_DateFormat to 'LL' to avoid date-fns crash (#40393)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ggazzo

.changeset/use-format-date-fallback.md

@@ -0,0 +1,5 @@
+---
+"@rocket.chat/meteor": patch
+---
+
+Fixes a `date-fns` crash on routes that mount before the public settings stream finishes loading. `useFormatDate` was passing `String(undefined)` (the literal `"undefined"`) to `formatDate` while `Message_DateFormat` was momentarily unloaded — `date-fns` rejects that token because it contains an unescaped `n`. The hook now uses `'LL'` as the default token via `useSetting`'s second argument, so the formatter always receives a valid format string.

apps/meteor/client/hooks/useFormatDate.ts

@@ -4,6 +4,6 @@ import { useCallback } from 'react';
 import { formatDate } from '../lib/utils/dateFormat';
 
 export const useFormatDate = () => {
-	const format = useSetting('Message_DateFormat');
-	return useCallback((time: string | Date | number) => formatDate(time, String(format)), [format]);
+	const format = useSetting('Message_DateFormat', 'LL');
+	return useCallback((time: string | Date | number) => formatDate(time, format), [format]);
 };