feat(stats): show work and time-off lengths (#66)

src/app/components/calendar-year/calendar-year.ts

@@ -762,6 +762,10 @@ export class CalendarYear {
 		this.userInput.remainingVacationDaysSignal.set([]);
 	}
 
+	protected formatStatistic(value: number | null): string {
+		return value === null ? '—' : value.toLocaleString(this.translationService.locale());
+	}
+
 	protected openStatistics(): void {
 		if (!this.displayedPlan() || this.statisticsDialog) return;
 		const dialog = this.dialog.open(this.statisticsTemplate(), {