feat(signing): internal "who signed" + completion email alerts to configurable recipients

Adds a per-port `signing_notification_recipients` setting (users / roles /
explicit emails via the existing RecipientPicker) and fires a branded
internal email on (a) each party signing and (b) full completion —
replicating the legacy "Document Signed" / "EOI Complete Update Status"
Activepieces flows that staff relied on.

- New branded template `signing-status-notification.tsx` (per-signer
  progress + completion variants, deep-links into the CRM).
- New `sendSigningStatusNotification` resolver in document-signing-emails:
  resolves recipients, falls back to the port reply-to (sales@) when the
  list is empty so alerts are never silently dropped, per-recipient send.
- Wired into `handleRecipientSigned` (first signed transition) and
  `handleDocumentCompleted` (idempotent, fires once) — reached by both the
  Documenso webhook and the 5-min poll. Fully guarded so a notification
  failure never undoes a signing side effect. Respects EMAIL_REDIRECT_TO.
- Admin UI: `Document signing alerts` recipients card in settings.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012iJPYbh5X53iBh9h7ffQoy

tests/unit/email/signing-status-notification.test.ts

@@ -0,0 +1,50 @@
+import { describe, expect, it } from 'vitest';
+
+import { signingStatusNotificationEmail } from '@/lib/email/templates/signing-status-notification';
+
+describe('signingStatusNotificationEmail', () => {
+  it('renders a per-signer "has signed" alert with progress + CRM link', async () => {
+    const { subject, html, text } = await signingStatusNotificationEmail({
+      event: 'signed',
+      documentLabel: 'Expression of Interest',
+      clientName: 'Jane Doe',
+      portName: 'Port Nimara',
+      crmUrl: 'https://crm.portnimara.com/port-nimara/documents/abc',
+      signerName: 'Jane Doe',
+      signerRole: 'client',
+      signedCount: 1,
+      totalCount: 3,
+    });
+
+    // Subject names who signed + the deal so sales can triage at a glance.
+    expect(subject).toContain('Jane Doe');
+    expect(subject).toContain('signed');
+    // Body states the signing event, the document, and progress.
+    expect(html).toContain('Jane Doe');
+    expect(html).toContain('has signed');
+    expect(html).toContain('Expression of Interest');
+    expect(html).toContain('1 of 3');
+    // Internal recipients get a deep link into the CRM, not a signing link.
+    expect(html).toContain('https://crm.portnimara.com/port-nimara/documents/abc');
+    expect(text).toContain('Jane Doe');
+    expect(text).toContain('1 of 3');
+  });
+
+  it('renders a completion alert when all parties have signed', async () => {
+    const { subject, html, text } = await signingStatusNotificationEmail({
+      event: 'completed',
+      documentLabel: 'Sales Contract',
+      clientName: 'Acme Holdings',
+      portName: 'Port Nimara',
+      crmUrl: 'https://crm.portnimara.com/port-nimara/documents/xyz',
+    });
+
+    expect(subject).toContain('Acme Holdings');
+    expect(subject.toLowerCase()).toContain('fully signed');
+    expect(html).toContain('all parties');
+    expect(html).toContain('Sales Contract');
+    expect(html).toContain('Acme Holdings');
+    expect(html).toContain('https://crm.portnimara.com/port-nimara/documents/xyz');
+    expect(text).toContain('Acme Holdings');
+  });
+});