Refactor logging implementation and enhance authentication logging

logger.js

@@ -4,13 +4,13 @@ const logger = createLogger({
     level: 'info',
     format: format.combine(
         format.timestamp(),
-        format.json()
+        format.printf(info => `${info.timestamp} ${info.level}: ${info.message}`)
     ),
     transports: [
         new transports.Console(),
-        new transports.File({ filename: 'app.log' })
+        new transports.File({ filename: '/data/app.log' })
     ]
-});
+}); 
 
 module.exports = logger;