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/Player/PlayerState.cs

@@ -0,0 +1,30 @@
+using System;
+using UnityEngine;
+
+public class PlayerState : MonoBehaviour
+{
+    public int Lives = 3;
+    public int TotalCoins { get; private set; }
+    public bool HasKey { get; private set; }
+
+    public event EventHandler<TreasureType> OnPlayerTakeItem;
+
+    public void AddCoin()
+    {
+        TotalCoins++;
+        OnPlayerTakeItem?.Invoke(this, TreasureType.Coin);
+        Debug.Log($"Player has {TotalCoins} coins");
+    }
+
+    public void SetKey()
+    {
+        HasKey = true;
+        OnPlayerTakeItem?.Invoke(this, TreasureType.Key);
+        Debug.Log("Player has key");
+    }
+
+    public void RemoveKey()
+    {
+        HasKey = false;
+    }
+}