feat: mail telegram and cron check

lib/mail.ts

@@ -0,0 +1,10 @@
+import nodemailer from "nodemailer";
+
+export async function sendMail(to: string, subject: string, text: string): Promise<void> {
+  const t = nodemailer.createTransport({
+    host: process.env.SMTP_HOST,
+    port: Number(process.env.SMTP_PORT ?? 587),
+    auth: { user: process.env.SMTP_USER, pass: process.env.SMTP_PASS },
+  });
+  await t.sendMail({ from: process.env.MAIL_FROM, to, subject, text });
+}