fix: complete email template and CMS page fixes for production

- Fix email templates list endpoint to handle both schema variations
- Add migration for default CMS pages with language-specific columns
- Create debug script to identify 500 error causes
- Update CMS migration to use correct column names (title_en/de, content_en/de)

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

Co-Authored-By: Claude <noreply@anthropic.com>

backend/src/routes/adminEmail.js

@@ -160,20 +160,35 @@ router.get('/templates', adminAuth, async (req, res) => {
       .orderBy('template_key');
 
     // Parse variables JSON and format for multi-language support
-    const formattedTemplates = templates.map(template => ({
-      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
-    }));
+    const formattedTemplates = templates.map(template => {
+      const result = {
+        id: template.id,
+        template_key: template.template_key,
+        variables: template.variables ? JSON.parse(template.variables) : [],
+        updated_at: template.updated_at
+      };
+      
+      // Handle both old and new schema formats
+      if (template.subject_en !== undefined) {
+        // New schema with language columns
+        result.subject_en = template.subject_en;
+        result.body_html_en = template.body_html_en;
+        result.body_text_en = template.body_text_en;
+        result.subject_de = template.subject_de;
+        result.body_html_de = template.body_html_de;
+        result.body_text_de = template.body_text_de;
+      } else {
+        // Old schema - use basic columns for both languages
+        result.subject_en = template.subject;
+        result.body_html_en = template.body_html;
+        result.body_text_en = template.body_text;
+        result.subject_de = template.subject;
+        result.body_html_de = template.body_html;
+        result.body_text_de = template.body_text;
+      }
+      
+      return result;
+    });
 
     res.json(formattedTemplates);
   } catch (error) {