feat: mail telegram and cron check

lib/scheduler.ts

@@ -0,0 +1,35 @@
+// Ruft die Cron-Route alle 15 Minuten im Production-Prozess auf.
+// Fehler werden nur geloggt; der nächste Intervall versucht es erneut.
+let timer: ReturnType<typeof setInterval> | null = null;
+
+export function startScheduler(baseUrl: string, intervalMs = 15 * 60 * 1000): () => void {
+  if (timer) return stopScheduler;
+  const secret = process.env.CRON_SECRET ?? "";
+  const run = async () => {
+    try {
+      const res = await fetch(`${baseUrl}/api/cron/check`, {
+        headers: { "x-cron-secret": secret },
+      });
+      if (!res.ok) console.error(`cron check failed: ${res.status}`);
+    } catch (e) {
+      console.error("cron check error", e);
+    }
+  };
+  void run();
+  timer = setInterval(() => void run(), intervalMs);
+  return stopScheduler;
+}
+
+export function stopScheduler(): void {
+  if (timer) {
+    clearInterval(timer);
+    timer = null;
+  }
+}
+
+export function ensureSchedulerStarted(): void {
+  if (process.env.NODE_ENV !== "production") return;
+  if (timer) return;
+  const baseUrl = process.env.APP_URL ?? `http://localhost:${process.env.PORT ?? 3000}`;
+  startScheduler(baseUrl);
+}