fix: add language detection from app_settings and fix activity_logs schema

- Enhanced language detection priority in email processor:
  1. Event-specific language
  2. App settings general_default_language (NEW)
  3. Email config default_language
  4. Domain-based detection
- Fixed activity_logs insertion error by using logActivity function
- Fixed 500 error on resend email endpoint
- Emails now respect language selected in settings page

backend/src/services/emailProcessor.js

@@ -73,7 +73,19 @@ async function getRecipientLanguage(email, eventId = null) {
     }
   }
   
-  // Second priority: Check email configs for default language
+  // Second priority: Check app_settings for general default language
+  try {
+    const langSetting = await db('app_settings')
+      .where('setting_key', 'general_default_language')
+      .first();
+    if (langSetting && langSetting.setting_value) {
+      return langSetting.setting_value;
+    }
+  } catch (error) {
+    logger.error('Error fetching app settings language:', error);
+  }
+  
+  // Third priority: Check email configs for default language
   try {
     const emailConfig = await db('email_configs').first();
     if (emailConfig && emailConfig.default_language) {
@@ -83,7 +95,7 @@ async function getRecipientLanguage(email, eventId = null) {
     logger.error('Error fetching email config language:', error);
   }
   
-  // Third priority: Check if the email domain suggests German
+  // Fourth priority: Check if the email domain suggests German
   if (email) {
     const germanDomains = ['.de', '.at', '.ch', '.li'];
     const domain = email.toLowerCase();