feat: add Winston logger setup

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/utils/logger.js

@@ -0,0 +1,28 @@
+import winston from 'winston';
+
+const logger = winston.createLogger({
+  level: process.env.LOG_LEVEL || 'info',
+  format: winston.format.combine(
+    winston.format.timestamp(),
+    winston.format.errors({ stack: true }),
+    winston.format.json()
+  ),
+  defaultMeta: { service: 'teleuploader' },
+  transports: [
+    // Write all logs including error logs to file
+    new winston.transports.File({ filename: 'logs/error.log', level: 'error' }),
+    new winston.transports.File({ filename: 'logs/combined.log' })
+  ]
+});
+
+// If not production, also log to console
+if (process.env.NODE_ENV !== 'production') {
+  logger.add(new winston.transports.Console({
+    format: winston.format.combine(
+      winston.format.colorize(),
+      winston.format.simple()
+    )
+  }));
+}
+
+export default logger;