Add player controller, state management, and input handling

- Implemented PlayerController.cs to manage player movement and actions.
- Created PlayerState.cs to track player lives, coins, and key status.
- Added CameraFollow.cs for smooth camera movement following the player.
- Developed Character.cs as an abstract class for character behavior.
- Introduced Enums.cs for defining TreasureType and MapElementType.
- Added IDoor interface for door interactions.
- Created InputActions.cs for handling player input actions.
- Implemented MainMenu.cs for basic menu functionality including play and exit options.

Assets/Scripts/Environment/MapElements/MapElement.cs

@@ -0,0 +1,16 @@
+using UnityEngine;
+using UnityEngine.UIElements;
+
+public class MapElement : MonoBehaviour, IMapElement
+{
+    [SerializeField]
+    private MapElementSO _elementSO;
+    public MapElementSO ElementSO => _elementSO;
+    public bool IsEnabled { get; set; } = true;
+
+    public Transform GlobalTransform { get; set; }
+
+    public virtual void Hit()
+    {
+    }
+}