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 <noreply@anthropic.com>

backend/src/routes/adminEmail.js

@@ -159,10 +159,20 @@ router.get('/templates', adminAuth, async (req, res) => {
       .select('*')
       .orderBy('template_key');
 
-    // Parse variables JSON
+    // Parse variables JSON and format for multi-language support
     const formattedTemplates = templates.map(template => ({
-      ...template,
-      variables: template.variables ? JSON.parse(template.variables) : []
+      id: template.id,
+      template_key: template.template_key,
+      // English versions
+      subject_en: template.subject_en || template.subject,
+      body_html_en: template.body_html_en || template.body_html,
+      body_text_en: template.body_text_en || template.body_text,
+      // German versions
+      subject_de: template.subject_de || template.subject_en || template.subject,
+      body_html_de: template.body_html_de || template.body_html_en || template.body_html,
+      body_text_de: template.body_text_de || template.body_text_en || template.body_text,
+      variables: template.variables ? JSON.parse(template.variables) : [],
+      updated_at: template.updated_at
     }));
 
     res.json(formattedTemplates);
@@ -184,8 +194,18 @@ router.get('/templates/:key', adminAuth, async (req, res) => {
     }
 
     res.json({
-      ...template,
-      variables: template.variables ? JSON.parse(template.variables) : []
+      id: template.id,
+      template_key: template.template_key,
+      // English versions
+      subject_en: template.subject_en || template.subject,
+      body_html_en: template.body_html_en || template.body_html,
+      body_text_en: template.body_text_en || template.body_text,
+      // German versions
+      subject_de: template.subject_de || template.subject_en || template.subject,
+      body_html_de: template.body_html_de || template.body_html_en || template.body_html,
+      body_text_de: template.body_text_de || template.body_text_en || template.body_text,
+      variables: template.variables ? JSON.parse(template.variables) : [],
+      updated_at: template.updated_at
     });
   } catch (error) {
     console.error('Email template fetch error:', error);
@@ -196,8 +216,10 @@ router.get('/templates/:key', adminAuth, async (req, res) => {
 // Update email template
 router.put('/templates/:key', [
   adminAuth,
-  body('subject').notEmpty().withMessage('Subject is required'),
-  body('body_html').notEmpty().withMessage('HTML body is required')
+  body('subject_en').optional().notEmpty().withMessage('English subject cannot be empty'),
+  body('subject_de').optional().notEmpty().withMessage('German subject cannot be empty'),
+  body('body_html_en').optional().notEmpty().withMessage('English HTML body cannot be empty'),
+  body('body_html_de').optional().notEmpty().withMessage('German HTML body cannot be empty')
 ], async (req, res) => {
   try {
     const errors = validationResult(req);
@@ -205,29 +227,38 @@ router.put('/templates/:key', [
       return res.status(400).json({ errors: errors.array() });
     }
 
-    const { subject, body_html, body_text } = req.body;
+    const {
+      subject_en, subject_de,
+      body_html_en, body_html_de,
+      body_text_en, body_text_de
+    } = req.body;
+
+    const updateData = {
+      updated_at: new Date()
+    };
+
+    // Only update provided fields
+    if (subject_en !== undefined) updateData.subject_en = subject_en;
+    if (subject_de !== undefined) updateData.subject_de = subject_de;
+    if (body_html_en !== undefined) updateData.body_html_en = body_html_en;
+    if (body_html_de !== undefined) updateData.body_html_de = body_html_de;
+    if (body_text_en !== undefined) updateData.body_text_en = body_text_en || '';
+    if (body_text_de !== undefined) updateData.body_text_de = body_text_de || '';
 
     const updated = await db('email_templates')
       .where('template_key', req.params.key)
-      .update({
-        subject,
-        body_html,
-        body_text: body_text || '',
-        updated_at: new Date()
-      });
+      .update(updateData);
 
     if (!updated) {
       return res.status(404).json({ error: 'Template not found' });
     }
 
     // Log activity
-    await db('activity_logs').insert({
-      activity_type: 'email_template_updated',
-      actor_type: 'admin',
-      actor_id: req.admin.id,
-      actor_name: req.admin.username,
-      metadata: JSON.stringify({ template_key: req.params.key })
-    });
+    await logActivity('email_template_updated',
+      { template_key: req.params.key },
+      null,
+      { type: 'admin', id: req.admin.id, name: req.admin.username }
+    );
 
     res.json({ message: 'Email template updated successfully' });
   } catch (error) {
@@ -247,12 +278,17 @@ router.post('/templates/:key/preview', adminAuth, async (req, res) => {
       return res.status(404).json({ error: 'Template not found' });
     }
 
-    const { preview_data } = req.body;
+    const { preview_data, language = 'en' } = req.body;
     
-    // Replace variables in template
-    let htmlContent = template.body_html;
-    let textContent = template.body_text || '';
-    let subject = template.subject;
+    // Get the appropriate language version
+    const subjectField = language === 'de' && template.subject_de ? 'subject_de' : 'subject_en';
+    const htmlField = language === 'de' && template.body_html_de ? 'body_html_de' : 'body_html_en';
+    const textField = language === 'de' && template.body_text_de ? 'body_text_de' : 'body_text_en';
+    
+    // Handle backward compatibility
+    let htmlContent = template[htmlField] || template.body_html || '';
+    let textContent = template[textField] || template.body_text || '';
+    let subject = template[subjectField] || template.subject || '';
 
     if (preview_data) {
       Object.keys(preview_data).forEach(key => {
@@ -266,7 +302,8 @@ router.post('/templates/:key/preview', adminAuth, async (req, res) => {
     res.json({
       subject,
       body_html: htmlContent,
-      body_text: textContent
+      body_text: textContent,
+      language
     });
   } catch (error) {
     console.error('Email template preview error:', error);