refactor: item 29 cleanup

F16 F17 F18 F19 F20 F21: import polling backs off and pauses in a hidden tab, one date format module, fake timers in the import tests, error codes instead of raw messages, one safe storage wrapper, dead code.

src/components/stats/PileStats.jsx

@@ -6,11 +6,12 @@ import StatTile from './StatTile.jsx';
 import GameRow from './GameRow.jsx';
 import {formatPlaytime} from '../../utils/games.js';
 import {formatDecimal} from '../../utils/stats.js';
+import {formatDate} from '../../utils/format.js';
 
 export default function PileStats({pile, linked = true}) {
     const {t, i18n} = useTranslation();
     const since = pile.oldestUnplayed
-        ? new Date(pile.oldestUnplayed.inLibrarySince).toLocaleDateString(i18n.language, {dateStyle: 'medium'})
+        ? formatDate(pile.oldestUnplayed.inLibrarySince, i18n.language, {dateStyle: 'medium'})
         : null;
     return (
         <StatsSection title={t('STATS.PILE.TITLE')} icon={Inbox}>