refactoring: TypeScript migration, security fixes,

client/src/utils/formatters.ts

@@ -0,0 +1,31 @@
+import type { AssignmentsMap } from '../types'
+
+export function formatDate(dateStr: string | null | undefined, locale: string): string | null {
+  if (!dateStr) return null
+  return new Date(dateStr + 'T00:00:00').toLocaleDateString(locale, {
+    weekday: 'short', day: 'numeric', month: 'short',
+  })
+}
+
+export function formatTime(timeStr: string | null | undefined, locale: string, timeFormat: string): string {
+  if (!timeStr) return ''
+  try {
+    const parts = timeStr.split(':')
+    const h = Number(parts[0]) || 0
+    const m = Number(parts[1]) || 0
+    if (isNaN(h)) return timeStr
+    if (timeFormat === '12h') {
+      const period = h >= 12 ? 'PM' : 'AM'
+      const h12 = h === 0 ? 12 : h > 12 ? h - 12 : h
+      return `${h12}:${String(m).padStart(2, '0')} ${period}`
+    }
+    const str = `${String(h).padStart(2, '0')}:${String(m).padStart(2, '0')}`
+    return locale?.startsWith('de') ? `${str} Uhr` : str
+  } catch { return timeStr }
+}
+
+export function dayTotalCost(dayId: number, assignments: AssignmentsMap, currency: string): string | null {
+  const da = assignments[String(dayId)] || []
+  const total = da.reduce((s, a) => s + (parseFloat(a.place?.price || '') || 0), 0)
+  return total > 0 ? `${total.toFixed(0)} ${currency}` : null
+}