Add Email DNS upsert for Stalwart DKIM, MX, and SPF.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/mail-dns/mail-dns.ts

@@ -0,0 +1,56 @@
+export const MAIL_IPV4 = '185.214.101.41';
+export const MAIL_HOSTNAME = 'mail.meshkee.com';
+export const MAIL_MX_PRIORITY = 10;
+export const MAIL_SPF = `v=spf1 ip4:${MAIL_IPV4} -all`;
+export const MAIL_DMARC = 'v=DMARC1; p=none';
+
+export type MailDkimKey = {
+  selector: string;
+  text: string;
+};
+
+export function parseDkimPaste(
+  raw: string,
+  expectedKind: 'ed25519' | 'rsa',
+): MailDkimKey {
+  const input = raw.trim();
+  if (!input) {
+    throw new Error(`Paste the ${expectedKind} DKIM line from Stalwart.`);
+  }
+
+  const quoted = [...input.matchAll(/"([^"]*)"/g)].map((match) => match[1]).join('');
+  const compact = input.replace(/[()\n\r\t]+/g, ' ').replace(/\s+/g, ' ').trim();
+  const blob = (quoted || compact).replace(/"\s+"/g, '');
+
+  const txtMatch = blob.match(/v=DKIM1[\s\S]*/i);
+  let text = (txtMatch ? txtMatch[0] : blob).trim();
+  text = text.replace(/^"+|"+$/g, '').replace(/\s+/g, ' ').replace(/[.\s]+$/g, '').trim();
+  if (!/^v=DKIM1/i.test(text)) {
+    throw new Error(
+      `Could not find a v=DKIM1 value in the ${expectedKind} field. Paste the Stalwart zone line.`,
+    );
+  }
+
+  const kind = /k=ed25519/i.test(text)
+    ? 'ed25519'
+    : /k=rsa/i.test(text)
+      ? 'rsa'
+      : null;
+  if (kind && kind !== expectedKind) {
+    throw new Error(
+      `That paste is ${kind} DKIM. Put it in the ${kind === 'ed25519' ? 'Ed25519' : 'RSA'} field.`,
+    );
+  }
+
+  const nameMatch = compact.match(/([a-z0-9][a-z0-9-]*)\._domainkey/i);
+  if (!nameMatch) {
+    throw new Error(
+      'Include the selector name (for example v1-ed25519-20260831._domainkey) from the Stalwart zone file.',
+    );
+  }
+
+  return {
+    selector: nameMatch[1].toLowerCase(),
+    text,
+  };
+}