feat(deps): adopt react-email for portal-auth template

Migrates the activation + reset email templates from hand-strung HTML
strings to React components rendered via @react-email/components.

Concrete wins this lands:
- React auto-escapes interpolation — drops the hand-rolled escapeHtml()
  helper. Eliminates the entire class of "I forgot to escape" XSS bugs.
- @react-email primitives (Button, Hr, Link, Text) render to
  Outlook/Gmail/AppleMail-safe inline-styled HTML.
- JSX over template strings makes the templates editable / reviewable.
- Sets the pattern for the remaining 7 templates (crm-invite,
  document-signing, inquiry-*, notification-digest, admin-email-change,
  residential-inquiry). Migrate opportunistically when those files are
  next touched.

The shell (logo, blurred background, table-based wrapper) stays via
renderShell so this is a strictly inner-body migration — visual parity
preserved.

Vitest config: added @vitejs/plugin-react so .tsx files imported by
tests (transitively via the service that uses the template) transform
correctly under Next's tsconfig `jsx: 'preserve'` setting.

Verified: tsc clean, vitest 1293/1293 pass.

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

src/lib/services/portal-auth.service.ts

@@ -147,7 +147,7 @@ async function issueActivationToken(
   const link = `${env.APP_URL}/portal/activate?token=${encodeURIComponent(raw)}`;
   const subjectOverride = await loadSubjectOverride(portId, 'portal_activation');
   const branding = await getBrandingShell(portId);
-  const { subject, html, text } = activationEmail(
+  const { subject, html, text } = await activationEmail(
     {
       portName,
       link,
@@ -408,7 +408,7 @@ export async function requestPasswordReset(email: string): Promise<void> {
   const link = `${env.APP_URL}/portal/reset-password?token=${encodeURIComponent(raw)}`;
   const subjectOverride = await loadSubjectOverride(user.portId, 'portal_reset');
   const branding = await getBrandingShell(user.portId);
-  const { subject, html, text } = resetEmail(
+  const { subject, html, text } = await resetEmail(
     {
       portName,
       link,