Add main menu scene, setup framework for orientation switching

Assets/Scripts/UI/MainMenu.cs

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+using UnityEngine;
+using UnityEngine.SceneManagement;
+
+public class MainMenu : MonoBehaviour
+{
+    public void StartGame()
+    {
+        // Replace with the actual scene name as set in Build Settings
+        SceneManager.LoadScene("AppleHillsOverworld");
+    }
+
+    public void QuitGame()
+    {
+        Application.Quit();
+#if UNITY_EDITOR
+        UnityEditor.EditorApplication.isPlaying = false;
+#endif
+    }
+}

Assets/Scripts/UI/MainMenu.cs.meta

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+fileFormatVersion: 2
+guid: 1db41e23e1963544989e5298f201e730