fix: photo upload issues with file limit and date formatting

- Add 20-file limit validation to PhotoUpload component
- Prevent Multer "Unexpected field" errors by enforcing client-side limit
- Fix JSON parsing error in dateFormatter when value is already an object
- Add missing translation keys for upload error messages
- Handle both string and object values for date format settings

These fixes resolve the 400 error when uploading more than 20 files
and the "Unexpected token o in JSON" error during email queue creation.

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

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

backend/src/utils/dateFormatter.js

@@ -11,7 +11,21 @@ async function formatDate(date, language = 'en') {
   try {
     // Get date format setting from database
     const setting = await db('app_settings').where('setting_key', 'general_date_format').first();
-    const dateConfig = setting ? JSON.parse(setting.setting_value) : DEFAULT_FORMAT;
+    let dateConfig = DEFAULT_FORMAT;
+    
+    if (setting && setting.setting_value) {
+      // Handle both string and object values
+      if (typeof setting.setting_value === 'string') {
+        try {
+          dateConfig = JSON.parse(setting.setting_value);
+        } catch (e) {
+          console.warn('Failed to parse date format setting:', e.message);
+          dateConfig = DEFAULT_FORMAT;
+        }
+      } else {
+        dateConfig = setting.setting_value;
+      }
+    }
     
     const dateObj = date instanceof Date ? date : new Date(date);