Implement multi-language email templates

- Add language columns to email_templates table (subject_en/de, body_html_en/de, body_text_en/de)
- Update adminEmail.js routes to support language-specific templates
- Create EmailProcessor service to handle language selection based on recipient
- Update EmailConfigPage component with language tabs similar to CMS pages
- Add German translations for all email templates
- Update all email queue usage to use proper template keys
- Add missing email templates (gallery_expired, archive_complete)
- Integrate email processor service into main server startup

The system now automatically selects the appropriate language (English/German) based on the recipient's email domain or preferences.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

backend/src/services/expirationChecker.js

@@ -1,6 +1,7 @@
 const cron = require('node-cron');
 const { db } = require('../database/db');
 const { archiveEvent } = require('./archiveService');
+const { queueEmail } = require('./emailProcessor');
 const logger = require('../utils/logger');
 
 function startExpirationChecker() {
@@ -28,7 +29,7 @@ async function checkExpirations() {
       // Check if warning email already sent
       const existingWarning = await db('email_queue')
         .where('event_id', event.id)
-        .where('email_type', 'warning')
+        .where('email_type', 'expiration_warning')
         .first();
       
       if (!existingWarning) {
@@ -55,15 +56,12 @@ async function queueExpirationWarning(event) {
   const daysRemaining = Math.ceil((new Date(event.expires_at) - new Date()) / (1000 * 60 * 60 * 24));
   
   // Queue email to host
-  await db('email_queue').insert({
-    event_id: event.id,
-    recipient_email: event.host_email,
-    email_type: 'warning',
-    email_data: JSON.stringify({
-      event_name: event.event_name,
-      days_remaining: daysRemaining,
-      share_link: event.share_link
-    })
+  await queueEmail(event.id, event.host_email, 'expiration_warning', {
+    host_name: event.host_email.split('@')[0],
+    event_name: event.event_name,
+    days_remaining: daysRemaining.toString(),
+    expiration_date: new Date(event.expires_at).toLocaleDateString(),
+    gallery_link: event.share_link
   });
   
   logger.info(`Queued expiration warning for event ${event.slug}`);
@@ -75,25 +73,16 @@ async function handleExpiredEvent(event) {
     await db('events').where('id', event.id).update({ is_active: false });
     
     // Queue expiration emails
-    await db('email_queue').insert([
-      {
-        event_id: event.id,
-        recipient_email: event.host_email,
-        email_type: 'expiration',
-        email_data: JSON.stringify({
-          event_name: event.event_name
-        })
-      },
-      {
-        event_id: event.id,
-        recipient_email: event.admin_email,
-        email_type: 'expiration',
-        email_data: JSON.stringify({
-          event_name: event.event_name,
-          event_slug: event.slug
-        })
-      }
-    ]);
+    await queueEmail(event.id, event.host_email, 'gallery_expired', {
+      event_name: event.event_name,
+      admin_email: event.admin_email
+    });
+    
+    // Also notify admin
+    await queueEmail(event.id, event.admin_email, 'gallery_expired', {
+      event_name: event.event_name,
+      admin_email: event.admin_email
+    });
     
     // Start archiving process
     await archiveEvent(event);