fix(safety): plug 3 EMAIL_REDIRECT_TO leaks + 10 unit tests + live smoke

A pre-import audit caught three places where outbound comms could escape
even with EMAIL_REDIRECT_TO set. Plugged each, added unit tests so the
behavior can't silently regress, and shipped a live smoke script the
operator can run before any production data import.

Leak 1: email-compose.service.ts (per-account user composer)
  Built its own nodemailer transporter and called sendMail() directly,
  bypassing the centralized sendEmail()'s redirect. Now mirrors the same
  redirect: when EMAIL_REDIRECT_TO is set, "to" is rewritten, "cc" is
  dropped, and the subject is prefixed with "[redirected from <orig>]".

Leak 2: documenso-client.sendDocument()
  Tells Documenso to actually email the document. Recipient emails were
  rerouted at create-time (in pass-3) but a document created BEFORE the
  redirect was turned on could still trigger a real-client email. Now
  short-circuited when the redirect is set — returns the existing doc
  shape so downstream code doesn't see an unexpected null.

Leak 3: documenso-client.sendReminder()
  Same shape as sendDocument: emails a stored recipient address that may
  predate the redirect. Now short-circuits with a warn-level log.

Tests (tests/unit/comms-safety.test.ts):
  - createDocument rewrites recipients
  - generateDocumentFromTemplate rewrites both v1.13 formValues.*Email
    keys AND v2.x recipients[] arrays
  - sendDocument is short-circuited (no /send call)
  - sendReminder is short-circuited (no /remind call)
  - createDocument passes through unchanged when redirect unset
  - sendEmail rewrites to + subject for single recipient
  - sendEmail handles array of recipients (joined into subject prefix)
  - sendEmail passes through unchanged when redirect unset
  - Webhook worker reads process.env.EMAIL_REDIRECT_TO at dispatch time
    (no module-level caching that could miss a runtime flip)

Live smoke (scripts/smoke-test-redirect.ts):
  Monkey-patches nodemailer.createTransport, calls the real sendEmail()
  with a fake real-client address, verifies the captured outbound has
  the right "to" + subject. Run: `pnpm tsx scripts/smoke-test-redirect.ts`.
  Exits non-zero if the redirect failed for any reason — drop-in for a
  pre-deploy check.

Verification:
  pnpm exec tsc --noEmit       — 0 errors
  pnpm exec vitest run         — 936/936 (was 926, +10 new safety tests)
  pnpm tsx scripts/smoke-test-redirect.ts — PASS

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/smoke-test-redirect.ts

@@ -0,0 +1,108 @@
+/**
+ * Live smoke test for EMAIL_REDIRECT_TO.
+ *
+ * Actually calls `sendEmail()` (the centralized helper used by every
+ * outbound email path in the app) with a fake real-client address. The
+ * SMTP transporter is monkey-patched to capture the message instead of
+ * actually delivering it, so this is safe to run anywhere.
+ *
+ * Prints the captured `to` + `subject` so the operator can see with their
+ * own eyes that the redirect happened. Exits non-zero if the redirect
+ * failed for any reason.
+ *
+ * Usage:
+ *   pnpm tsx scripts/smoke-test-redirect.ts
+ */
+import 'dotenv/config';
+
+async function main() {
+  const expectedRedirect = process.env.EMAIL_REDIRECT_TO;
+  if (!expectedRedirect) {
+    console.error('FAIL: EMAIL_REDIRECT_TO is not set in env. Set it before running this test.');
+    process.exit(1);
+  }
+
+  console.log(`[smoke] EMAIL_REDIRECT_TO = ${expectedRedirect}`);
+  console.log('');
+
+  // Monkey-patch nodemailer's createTransport so we capture the call
+  // without actually delivering. This is the same pattern the unit
+  // tests use, but at the live import-time level so we're testing the
+  // exact code path that runs in production.
+  const nodemailer = await import('nodemailer');
+  const captured: Array<{ to: unknown; subject: unknown; from: unknown }> = [];
+  const originalCreateTransport = nodemailer.default.createTransport;
+  // @ts-expect-error monkey-patch
+  nodemailer.default.createTransport = () => ({
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    sendMail: async (msg: any) => {
+      captured.push({ to: msg.to, subject: msg.subject, from: msg.from });
+      return { messageId: '<smoke@test>', accepted: [msg.to], rejected: [] };
+    },
+  });
+
+  // Now import sendEmail (gets the patched transporter).
+  const { sendEmail } = await import('@/lib/email');
+
+  const realClientEmail = 'real-client-DO-NOT-EMAIL@example.test';
+  const realSubject = 'Important: Your contract is ready';
+
+  console.log('[smoke] calling sendEmail(...) with:');
+  console.log(`         to:      ${realClientEmail}`);
+  console.log(`         subject: "${realSubject}"`);
+  console.log('');
+
+  await sendEmail(realClientEmail, realSubject, '<p>Body unused for this smoke.</p>');
+
+  // Restore the original transport (be a good citizen).
+  // @ts-expect-error monkey-patch
+  nodemailer.default.createTransport = originalCreateTransport;
+
+  console.log('[smoke] captured outbound message:');
+  console.log(`         to:      ${captured[0]?.to}`);
+  console.log(`         subject: "${captured[0]?.subject}"`);
+  console.log(`         from:    ${captured[0]?.from}`);
+  console.log('');
+
+  // Assertions
+  let pass = true;
+
+  if (captured.length !== 1) {
+    console.error(`FAIL: expected exactly 1 sendMail call, got ${captured.length}`);
+    pass = false;
+  }
+
+  if (captured[0]?.to !== expectedRedirect) {
+    console.error(
+      `FAIL: outbound "to" was "${captured[0]?.to}", expected the redirect address "${expectedRedirect}"`,
+    );
+    pass = false;
+  }
+
+  if (
+    typeof captured[0]?.subject !== 'string' ||
+    !captured[0].subject.startsWith(`[redirected from ${realClientEmail}]`)
+  ) {
+    console.error(
+      `FAIL: subject did not get the [redirected from <orig>] prefix. Got: "${captured[0]?.subject}"`,
+    );
+    pass = false;
+  }
+
+  if (pass) {
+    console.log('PASS: EMAIL_REDIRECT_TO is intercepting outbound email correctly.');
+    console.log(
+      '      The "to" header matches the redirect, and the original recipient is preserved in the subject.',
+    );
+    process.exit(0);
+  } else {
+    console.error('');
+    console.error('Smoke test FAILED. Do not import production data until this is fixed.');
+    process.exit(1);
+  }
+}
+
+main().catch((err) => {
+  console.error('FATAL:', err);
+  process.exit(1);
+});