fix: email resend language and password display issues

- Added missing translation for admin.activities.email_resent in both EN and DE
- Fixed language detection in resend email to use email processor's priority system
- Fixed password security message showing German text in English emails
- Updated email processor to handle password placeholder and format dates properly
- Dates are now formatted according to language and system settings
- Password security message now displays in the correct language based on recipient

backend/src/services/emailProcessor.js

@@ -109,6 +109,9 @@ async function getRecipientLanguage(email, eventId = null) {
 
 // Process email template with variables
 async function processTemplate(template, variables, language = 'en') {
+  // Import date formatter
+  const { formatDate } = require('../utils/dateFormatter');
+  
   // Get the appropriate language fields
   const subjectField = language === 'de' ? 'subject_de' : 'subject_en';
   const htmlField = language === 'de' ? 'body_html_de' : 'body_html_en';
@@ -118,6 +121,27 @@ async function processTemplate(template, variables, language = 'en') {
   let subject = template[subjectField] || template.subject || '';
   let htmlBody = template[htmlField] || template.body_html || '';
   let textBody = template[textField] || template.body_text || '';
+  
+  // Process variables before template compilation
+  const processedVariables = { ...variables };
+  
+  // Handle password security message
+  if (processedVariables.gallery_password === '{{password_security_message}}') {
+    processedVariables.gallery_password = language === 'de' 
+      ? '(Aus Sicherheitsgründen nicht angezeigt)' 
+      : '(Not shown for security reasons)';
+  }
+  
+  // Format dates if they exist
+  if (processedVariables.event_date) {
+    processedVariables.event_date = await formatDate(processedVariables.event_date, language);
+  }
+  if (processedVariables.expiry_date) {
+    processedVariables.expiry_date = await formatDate(processedVariables.expiry_date, language);
+  }
+  if (processedVariables.archive_date) {
+    processedVariables.archive_date = await formatDate(processedVariables.archive_date, language);
+  }
 
   // Get branding settings for logo
   let logoUrl = '';
@@ -156,10 +180,10 @@ async function processTemplate(template, variables, language = 'en') {
   const htmlTemplate = Handlebars.compile(htmlBody);
   const textTemplate = Handlebars.compile(textBody);
   
-  // Process templates with variables
-  subject = subjectTemplate(variables);
-  htmlBody = htmlTemplate(variables);
-  textBody = textTemplate(variables);
+  // Process templates with processedVariables (includes formatted dates and security messages)
+  subject = subjectTemplate(processedVariables);
+  htmlBody = htmlTemplate(processedVariables);
+  textBody = textTemplate(processedVariables);
 
   // Wrap HTML body in styled template
   const styledHtmlBody = `