feat: enhance security logging and ensure rate limit blocks are properly tracked

- Add comprehensive logging for rate limit blocks with full request details
  - IP address (with proper proxy detection), user agent, headers, timestamps
  - Rate limit info (current count, limit, remaining, reset time)
  - Separate tracking for auth vs general endpoints

- Enhance authentication failure logging
  - JWT validation failures with detailed error info
  - Admin auth attempts without token
  - Failed token validation with user context
  - All events include IP, path, method, user agent

- Improve Winston logger configuration for production
  - Add automatic log rotation (10MB errors, 50MB combined)
  - Create separate security.log for auth/rate limit events
  - Ensure logs directory exists automatically
  - Add structured JSON format for log aggregation
  - Support container logging with LOG_TO_CONSOLE env var

- Create comprehensive documentation
  - Security logging guide with examples
  - Monitoring recommendations
  - Configuration reference

- Add test script to verify logging functionality

All rate limit settings remain configurable via admin panel:
- Window duration, max requests, auth limits
- Skip authenticated requests option
- Public endpoints only option

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

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

backend/src/services/emailProcessor.js

@@ -109,8 +109,9 @@ async function getRecipientLanguage(email, eventId = null) {
 
 // Process email template with variables
 async function processTemplate(template, variables, language = 'en') {
-  // Import date formatter
+  // Import date formatter and text formatters
   const { formatDate } = require('../utils/dateFormatter');
+  const { formatWelcomeMessage } = require('../utils/formatters');
   
   // Get the appropriate language fields
   const subjectField = language === 'de' ? 'subject_de' : 'subject_en';
@@ -142,6 +143,11 @@ async function processTemplate(template, variables, language = 'en') {
   if (processedVariables.archive_date) {
     processedVariables.archive_date = await formatDate(processedVariables.archive_date, language);
   }
+  
+  // Format welcome message for HTML display (preserve line breaks)
+  if (processedVariables.welcome_message) {
+    processedVariables.welcome_message = formatWelcomeMessage(processedVariables.welcome_message);
+  }
 
   // Get branding settings for logo
   let logoUrl = '';

backend/src/services/rateLimitService.js

@@ -177,13 +177,33 @@ async function createRateLimiter() {
       return shouldSkipRateLimit(req, currentConfig);
     },
     handler: (req, res) => {
-      const clientIp = req.headers['x-forwarded-for']?.split(',')[0]?.trim() || req.ip;
+      const clientIp = req.headers['x-forwarded-for']?.split(',')[0]?.trim() || 
+                     req.headers['x-real-ip'] || 
+                     req.connection.remoteAddress || 
+                     req.ip;
+      
+      // Enhanced logging for production analysis
       logger.warn('Rate limit exceeded', {
         ip: clientIp,
         path: req.path,
         method: req.method,
         authenticated: isAuthenticated(req),
-        tokenType: req.tokenType
+        tokenType: req.tokenType,
+        userAgent: req.headers['user-agent'],
+        referer: req.headers['referer'],
+        origin: req.headers['origin'],
+        timestamp: new Date().toISOString(),
+        headers: {
+          'x-forwarded-for': req.headers['x-forwarded-for'],
+          'x-real-ip': req.headers['x-real-ip']
+        },
+        requestUrl: req.originalUrl,
+        rateLimitInfo: {
+          limit: req.rateLimit?.limit,
+          current: req.rateLimit?.current,
+          remaining: req.rateLimit?.remaining,
+          resetTime: req.rateLimit?.resetTime ? new Date(req.rateLimit.resetTime).toISOString() : null
+        }
       });
       
       res.status(429).json({ 
@@ -217,10 +237,30 @@ async function createAuthRateLimiter() {
       return !currentConfig.enabled;
     },
     handler: (req, res) => {
-      const clientIp = req.headers['x-forwarded-for']?.split(',')[0]?.trim() || req.ip;
+      const clientIp = req.headers['x-forwarded-for']?.split(',')[0]?.trim() || 
+                     req.headers['x-real-ip'] || 
+                     req.connection.remoteAddress || 
+                     req.ip;
+      
+      // Enhanced logging for auth failures
       logger.warn('Auth rate limit exceeded', {
         ip: clientIp,
-        path: req.path
+        path: req.path,
+        method: req.method,
+        userAgent: req.headers['user-agent'],
+        timestamp: new Date().toISOString(),
+        headers: {
+          'x-forwarded-for': req.headers['x-forwarded-for'],
+          'x-real-ip': req.headers['x-real-ip'
+        },
+        requestUrl: req.originalUrl,
+        authType: req.path.includes('admin') ? 'admin' : 'gallery',
+        rateLimitInfo: {
+          limit: req.rateLimit?.limit,
+          current: req.rateLimit?.current,
+          remaining: req.rateLimit?.remaining,
+          resetTime: req.rateLimit?.resetTime ? new Date(req.rateLimit.resetTime).toISOString() : null
+        }
       });
       
       res.status(429).json({