feat: mail telegram and cron check

lib/notify-text.ts

@@ -0,0 +1,10 @@
+import { formatEuro } from "./vouchers";
+
+function formatDatum(d: string | Date): string {
+  if (typeof d === "string") return d;
+  return d.toLocaleDateString("de-DE", { day: "2-digit", month: "2-digit", year: "numeric" });
+}
+
+export function buildReminderText(v: { name: string; restCents: number; ablaufdatum: string | Date }): string {
+  return `Gutschein "${v.name}" läuft am ${formatDatum(v.ablaufdatum)} ab. Restguthaben: ${formatEuro(v.restCents)}.`;
+}