refactor: optimize PM2 config for single instance

- Change from cluster to fork mode for single instance
- Remove instances field (defaults to 1 in fork mode)
- Adjust memory limit to 138MB with 110MB heap
- Remove instance_var (not needed in fork mode)
- Clean up configuration (removed excessive comments)

Author: Wal33D

ecosystem.config.js

@@ -1,34 +1,23 @@
-// ecosystem.config.js
-// PM2 Configuration for Address Validation Service
-
 module.exports = {
   apps: [
     {
       name: 'address-validation-service',
       script: 'dist/server.js',
-
-      // Cluster mode with automatic CPU core detection
-      exec_mode: 'cluster',
-      instances: 'max', // Use all available CPU cores
-
-      // Memory management
-      max_memory_restart: '512M', // Restart if memory exceeds 512MB
-
-      // Restart behavior
+      exec_mode: 'fork',
+      max_memory_restart: '138M',
       autorestart: true,
-      watch: false, // Don't watch in production
+      watch: false,
       max_restarts: 10,
-      min_uptime: '20s', // App must run for 20s to be considered started
+      min_uptime: '20s',
+      restart_delay: 4000,
 
-      // Logging
       error_file: './logs/error.log',
       out_file: './logs/out.log',
       log_file: './logs/combined.log',
-      time: true, // Add timestamps to logs
+      time: true,
       merge_logs: true,
       log_date_format: 'YYYY-MM-DD HH:mm:ss Z',
 
-      // Environment variables
       env: {
         NODE_ENV: 'production',
         PORT: 3715,
@@ -39,27 +28,13 @@ module.exports = {
         LOG_LEVEL: 'debug',
       },
 
-      // Graceful shutdown
-      kill_timeout: 5000, // 5 seconds to gracefully shutdown
-      listen_timeout: 3000, // 3 seconds to be ready
-
-      // Performance optimizations
-      node_args: [
-        '--max-old-space-size=512', // Limit heap to 512MB
-        '--optimize-for-size', // Optimize for memory usage
-        '--gc-interval=100', // More frequent garbage collection
-      ].join(' '),
-
-      // Health check
-      cron_restart: '0 3 * * *', // Daily restart at 3 AM to prevent memory leaks
-
-      // Monitoring
-      instance_var: 'INSTANCE_ID', // Differentiate between cluster instances
+      kill_timeout: 5000,
+      listen_timeout: 3000,
 
-      // Zero-downtime reload
-      wait_ready: true, // Wait for ready signal
+      node_args: ['--max-old-space-size=110', '--optimize-for-size', '--gc-interval=100'].join(' '),
 
-      // Dependencies
+      cron_restart: '0 3 * * *',
+      wait_ready: true,
       post_update: ['npm install', 'npm run build'],
     },
   ],