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.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: edf40d39eadb17a4ebb0368b3ac5399a
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: