Add gin.Logger() middleware for HTTP request logging in dev mode

backend/cmd/server/main.go

@@ -133,6 +133,7 @@ func main() {
 
 	// Create a new Gin engine (router).
 	engine := gin.New()
+	engine.Use(gin.Logger()) // Log HTTP requests (shows method, path, status, latency)
 	engine.Use(gin.Recovery())
 
 	// Register API routes from the router.