Fix live test follow-up issues

src/app/dashboard/notdienst/page.tsx

@@ -4,7 +4,7 @@ import { Info, Calendar, ArrowRight, ShieldAlert } from "lucide-react";
 
 import { requireRole } from "@/lib/auth-utils";
 import { prisma } from "@/lib/prisma";
-import { getTargetMonthData } from "@/lib/date-utils";
+import { formatDateKey, getTargetMonthData } from "@/lib/date-utils";
 import { Button } from "@/components/ui/button";
 import { NotdienstEntry } from "./notdienst-entry";
 
@@ -45,6 +45,8 @@ export default async function NotdienstPage() {
 
   const targetData = getTargetMonthData();
   const { targetYear, targetMonth, monthName, isLocked } = targetData;
+  const targetMonthStart = new Date(Date.UTC(targetYear, targetMonth - 1, 1));
+  const targetMonthEnd = new Date(Date.UTC(targetYear, targetMonth, 1));
 
   const requiredDaysTotal = children.length * kita.notdienstMinPerChildPerMonth;
   const childIds = children.map((child) => child.id);
@@ -58,8 +60,8 @@ export default async function NotdienstPage() {
               kitaId,
               childId: { in: childIds },
               date: {
-                gte: new Date(targetYear, targetMonth - 1, 1),
-                lt: new Date(targetYear, targetMonth, 1),
+                gte: targetMonthStart,
+                lt: targetMonthEnd,
               },
             },
             select: { date: true },
@@ -77,7 +79,7 @@ export default async function NotdienstPage() {
         ])
       : [[], 0];
 
-  const selectedDates = availabilities.map((a) => a.date.toISOString());
+  const selectedDates = availabilities.map((a) => formatDateKey(a.date));
 
   return (
     <div className="mx-auto max-w-4xl px-4 py-8 sm:px-8">