fix(projects): scope email rollup to CRM types + re-render unstored previews

- The customer address often doubles as the admin notification target, so
  matching emails purely by recipient swept in system alerts (backup_failed,
  restore_failed, …). The recipient match is now restricted to CRM document
  types (quote_/contract_/invoice_/storno_); event-scoped mails still match
  by event_id.
- getEmailPreview now falls back to renderQueuedEmail() — re-rendering from
  the current template + the row's stored email_data — for emails sent before
  rendered_html capture, flagged exact:false with an amber 're-rendered' note.
  Only a missing template / no variables falls through to 'nothing stored'.

Known limitation: a customer with multiple projects sees their event_id=null
CRM mails under each (email_queue has no project_id).

backend/src/services/emailProcessor.js

@@ -772,6 +772,22 @@ async function sendTemplateEmail(to, templateKey, variables) {
   }
 }
 
+/**
+ * Render a queued email's HTML WITHOUT sending it. Used by the Project
+ * Overview cockpit to preview emails that predate the rendered_html column
+ * (so nothing was stored at send time). The result is rendered from the
+ * CURRENT template + the row's stored variables, so it's a faithful
+ * approximation rather than the exact bytes that were sent — callers flag
+ * it as a re-render. Returns null when the template no longer exists.
+ */
+async function renderQueuedEmail(templateKey, variables = {}, to = '') {
+  const template = await db('email_templates').where('template_key', templateKey).first();
+  if (!template) return null;
+  const language = await getRecipientLanguage(to, variables.eventId || null);
+  const { subject, htmlBody } = await processTemplate(template, variables, language);
+  return { subject, html: htmlBody };
+}
+
 // Process email queue.
 //
 // Options:
@@ -1074,6 +1090,7 @@ module.exports = {
   initializeTransporter,
   startEmailQueueProcessor,
   sendTemplateEmail,
+  renderQueuedEmail,
   processEmailQueue,
   queueEmail,
   stopEmailQueueProcessor,