voicemail: index messages, live event, email with the recording

services/voicemail.ts rescans a mailbox on Asterisk's MessageWaiting event
(and every mailbox on AMI connect) instead of watching files, upserts
voicemail_messages by msg_id, marks vanished ones deleted, sends
voicemail.new to the owner only, and emails the wav. Delete-after-email
uses AMI VoicemailRemove, and only when the audio was attached. Asterisk
24 has VoicemailMove/VoicemailRemove, so 04 §5.6 drops the renumbering
plan. New VOICEMAIL_DIR setting; e2e m4-t2 checks the email arrives
within 10 s with a playable attachment (SMTP sink shared with m3-t4).

Task: M4-T2

scripts/e2e/smtp-sink.mjs

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+// Just enough SMTP for nodemailer: no auth, no TLS, keeps every message (raw RFC 5322 text).
+import { createServer } from 'node:net';
+
+export async function smtpSink(port = 2525) {
+  const mails = [];
+  const server = createServer((sock) => {
+    let data = false;
+    let buf = '';
+    let msg = '';
+    sock.write('220 sink ESMTP\r\n');
+    sock.on('data', (d) => {
+      buf += d;
+      let i;
+      while ((i = buf.indexOf('\r\n')) >= 0) {
+        const line = buf.slice(0, i);
+        buf = buf.slice(i + 2);
+        if (data) {
+          if (line === '.') {
+            data = false;
+            mails.push(msg);
+            msg = '';
+            sock.write('250 ok\r\n');
+          } else msg += line.replace(/^\.\./, '.') + '\n';
+        } else if (/^EHLO/i.test(line)) sock.write('250-sink\r\n250 OK\r\n');
+        else if (/^DATA/i.test(line)) {
+          data = true;
+          sock.write('354 go\r\n');
+        } else if (/^QUIT/i.test(line)) sock.end('221 bye\r\n');
+        else sock.write('250 ok\r\n');
+      }
+    });
+  });
+  await new Promise((r) => server.listen(port, '127.0.0.1', r));
+  return { mails, server };
+}