feat: Make backend port configurable via PORT environment variable (defaults to 3001)

This allows changing the port without editing code:

ecosystem.config.js

@@ -7,7 +7,7 @@ module.exports = {
       cwd: '/path/to/award',
       env: {
         NODE_ENV: 'production',
-        PORT: 3001
+        PORT: 4000  // Change this to your preferred port
       },
       instances: 1,
       exec_mode: 'fork',
@@ -19,4 +19,4 @@ module.exports = {
       log_date_format: 'YYYY-MM-DD HH:mm:ss Z'
     }
   ]
-};
+};