Phase 0.3: migrate date formatting to date-fns

frontend/src/pages/AuditLog.tsx

@@ -8,6 +8,7 @@ import { Input } from '@/components/ui/Input';
 import { Button } from '@/components/ui/Button';
 import { EmptyState } from '@/components/ui/EmptyState';
 import { Badge } from '@/components/ui/Badge';
+import { formatDateTime } from '@/utils/date';
 
 export function AuditLogPage() {
   const { t } = useTranslation();
@@ -41,8 +42,7 @@ export function AuditLogPage() {
         cell: (info) => {
           const val = info.getValue();
           if (!val) return '—';
-          const date = new Date(val);
-          return date.toLocaleString('de-DE');
+          return formatDateTime(val) || '—';
         },
       },
       {

frontend/src/pages/Calendar.tsx

@@ -18,6 +18,7 @@ import { MonthView } from '@/components/calendar/MonthView';
 import { WeekView } from '@/components/calendar/WeekView';
 import { DayView } from '@/components/calendar/DayView';
 import { RangeView } from '@/components/calendar/RangeView';
+import { formatDateInput } from '@/utils/date';
 import { CalendarDetail } from '@/components/calendar/CalendarDetail';
 import { AppointmentModal } from '@/components/calendar/AppointmentModal';
 import { IcsControls } from '@/components/calendar/IcsControls';
@@ -488,7 +489,7 @@ export function CalendarPage() {
         <label className="text-xs text-secondary-600">{t('calendar.range.start')}</label>
         <input
           type="date"
-          value={rangeStart ? rangeStart.toISOString().slice(0, 10) : ''}
+          value={rangeStart ? formatDateInput(rangeStart) : ''}
           onChange={(e) => setRangeStart(e.target.value ? new Date(e.target.value) : null)}
           className="text-sm rounded-md border border-secondary-300 px-2 py-1"
           data-testid="calendar-range-start"
@@ -496,7 +497,7 @@ export function CalendarPage() {
         <label className="text-xs text-secondary-600">{t('calendar.range.end')}</label>
         <input
           type="date"
-          value={rangeEnd ? rangeEnd.toISOString().slice(0, 10) : ''}
+          value={rangeEnd ? formatDateInput(rangeEnd) : ''}
           onChange={(e) => setRangeEnd(e.target.value ? new Date(e.target.value) : null)}
           className="text-sm rounded-md border border-secondary-300 px-2 py-1"
           data-testid="calendar-range-end"

frontend/src/pages/Dashboard.tsx

@@ -3,6 +3,7 @@ import { useTranslation } from 'react-i18next';
 import { StatCard } from '@/components/shared/StatCard';
 import { ActivityFeed, ActivityItem } from '@/components/shared/ActivityFeed';
 import { useUnifiedContacts, useAuditLog } from '@/api/hooks';
+import { formatDateTime } from '@/utils/date';
 
 export function DashboardPage() {
   const { t } = useTranslation();
@@ -36,7 +37,7 @@ export function DashboardPage() {
         id: `${entry.timestamp}-${entry.user}-${entry.action}`,
         user: entry.user || 'System',
         action: entry.action || '',
-        time: entry.timestamp ? new Date(entry.timestamp).toLocaleString('de-DE') : '',
+        time: entry.timestamp ? (formatDateTime(entry.timestamp) || '') : '',
         avatarUrl: null,
       }));
 

frontend/src/pages/DmsTrash.tsx

@@ -8,6 +8,7 @@ import { useTranslation } from 'react-i18next';
 import { Link } from 'react-router-dom';
 import { Button } from '@/components/ui/Button';
 import { Card } from '@/components/ui/Card';
+import { formatDateShort } from '@/utils/date';
 import { Table, TableColumn } from '@/components/ui/Table';
 import { EmptyState } from '@/components/ui/EmptyState';
 import { Skeleton } from '@/components/ui/Skeleton';
@@ -79,7 +80,7 @@ export function DmsTrashPage() {
       sortable: true,
       accessor: (file) => file.deleted_at || '',
       render: (file) => file.deleted_at
-        ? new Date(file.deleted_at).toLocaleDateString()
+        ? (formatDateShort(file.deleted_at) || '—')
         : '—',
     },
     {