edited mailer and changed orchestration

Co-authored-by: Copilot <copilot@github.com>

backendV2/services/mailer/send.js

@@ -0,0 +1,13 @@
+import { transporter } from "./transporter.js";
+
+export async function sendMail({ to, subject, text, html }) {
+  const info = await transporter.sendMail({
+    from: '"Ausleihsystem" <noreply@mcs-medien.de>',
+    to,
+    subject,
+    text,
+    html,
+  });
+  console.log("Mail sent:", info.messageId);
+  return info;
+}