feat: add SMTP auth support for K3s migration

- Support SMTP_USER/SMTP_PASS env vars for authenticated SMTP
- Support SMTP_FROM env var for configurable sender address
- Auto-detect secure mode for port 465
- Backwards compatible: falls back to unauthenticated local relay

src/services/email.ts

@@ -1,20 +1,33 @@
 import nodemailer from "nodemailer";
 import logger from "./logger.js";
 
-const transporter = nodemailer.createTransport({
-  host: process.env.SMTP_HOST || "host.docker.internal",
-  port: Number(process.env.SMTP_PORT || 25),
-  secure: false,
+const smtpUser = process.env.SMTP_USER;
+const smtpPass = process.env.SMTP_PASS;
+const smtpHost = process.env.SMTP_HOST || "host.docker.internal";
+const smtpPort = Number(process.env.SMTP_PORT || 25);
+const smtpFrom = process.env.SMTP_FROM || "DocFast <noreply@docfast.dev>";
+const smtpSecure = smtpPort === 465;
+
+const transportConfig: any = {
+  host: smtpHost,
+  port: smtpPort,
+  secure: smtpSecure,
   connectionTimeout: 5000,
   greetingTimeout: 5000,
   socketTimeout: 10000,
   tls: { rejectUnauthorized: false },
-});
+};
+
+if (smtpUser && smtpPass) {
+  transportConfig.auth = { user: smtpUser, pass: smtpPass };
+}
+
+const transporter = nodemailer.createTransport(transportConfig);
 
 export async function sendVerificationEmail(email: string, code: string): Promise<boolean> {
   try {
     const info = await transporter.sendMail({
-      from: "DocFast <noreply@docfast.dev>",
+      from: smtpFrom,
       to: email,
       subject: "DocFast - Verify your email",
       text: `Your DocFast verification code is: ${code}\n\nThis code expires in 15 minutes.\n\nIf you didn't request this, ignore this email.`,