Fix server/client component boundary issue with reasonColor/reasonLabel helper functions by moving them to shared utils

src/app/dashboard/absence-card.tsx

@@ -4,6 +4,7 @@ import Link from "next/link";
 import { useMemo, useTransition } from "react";
 import { AbsenceReason } from "@prisma/client";
 import { Baby, CalendarX2, Check, ChevronRight, Loader2 } from "lucide-react";
+import { reasonColor, reasonLabel } from "@/lib/absence-utils";
 import { toast } from "sonner";
 
 import { reportAbsence } from "@/actions/absences";
@@ -331,14 +332,4 @@ function AbsenceRow({ absence }: { absence: AbsenceListItem }) {
   );
 }
 
-function reasonLabel(reason: AbsenceReason) {
-  if (reason === AbsenceReason.ILLNESS) return "Krank";
-  if (reason === AbsenceReason.VACATION) return "Urlaub";
-  return "Sonstiges";
-}
 
-function reasonColor(reason: AbsenceReason) {
-  if (reason === AbsenceReason.ILLNESS) return "var(--danger)";
-  if (reason === AbsenceReason.VACATION) return "var(--warn)";
-  return "var(--accent)";
-}