Add MainMenuUI component for game start and exit functionality; implement scene loading and browser detection

Assets/Scripts/UI/MainMenuUI.cs

@@ -0,0 +1,42 @@
+using System;
+using UnityEngine;
+using UnityEngine.SceneManagement;
+using UnityEngine.UI;
+using Object = UnityEngine.Object;
+
+namespace UI
+{
+    public class MainMenuUI : MonoBehaviour
+    {
+        [SerializeField] private Object mainScene;
+        [SerializeField] private Button exitButton;
+
+        private void OnEnable()
+        {
+            DetectIfBrowser();
+        }
+        
+        private void DetectIfBrowser()
+        {
+            if (Application.platform == RuntimePlatform.WebGLPlayer)
+            {
+                exitButton.gameObject.SetActive(false);
+            }
+        }
+
+        public void StartGame()
+        {
+            SceneManager.LoadScene(mainScene.name);
+        }
+
+        public void ExitGame()
+        {
+            if (Application.platform == RuntimePlatform.WebGLPlayer)
+            {
+                return;
+            }
+          
+            Application.Quit();
+        }
+    }
+}