Refactoring of the interaction system and preliminary integration of save/load functionality across the game. (#44)

### Interactables Architecture Refactor
- Converted composition to inheritance, moved from component-based to class-based interactables. No more requirement for chain of "Interactable -> Item" etc.
- Created `InteractableBase` abstract base class with common functionality that replaces the old component
- Specialized child classes: `Pickup`, `ItemSlot`, `LevelSwitch`, `MinigameSwitch`, `CombinationItem`, `OneClickInteraction` are now children classes
- Light updates to the interactable inspector, moved some things arround, added collapsible inspector sections in the  UI for better editor experience

### State Machine Integration
- Custom `AppleMachine` inheritong from Pixelplacement's StateMachine which implements our own interface for saving, easy place for future improvements
- Replaced all previous StateMachines by `AppleMachine`
- Custom `AppleState`  extends from default `State`. Added serialization, split state logic into "EnterState", "RestoreState", "ExitState" allowing for separate logic when triggering in-game vs loading game
- Restores directly to target state without triggering transitional logic
- Migration tool converts existing instances

### Prefab Organization
- Saved changes from scenes into prefabs
- Cleaned up duplicated components, confusing prefabs hierarchies
- Created prefab variants where possible
- Consolidated Environment prefabs and moved them out of Placeholders subfolder into main Environment folder
- Organized item prefabs from PrefabsPLACEHOLDER into proper Items folder
- Updated prefab references - All scene references updated to new locations
- Removed placeholder files from Characters, Levels, UI, and Minigames folders

### Scene Updates
- Quarry scene with major updates
- Saved multiple working versions (Quarry, Quarry_Fixed, Quarry_OLD)
- Added proper lighting data
- Updated all interactable components to new architecture

### Minor editor tools
- New tool for testing cards from an editor window (no in-scene object required)
- Updated Interactable Inspector
- New debug option to opt in-and-out of the save/load system
- Tooling for easier migration

Co-authored-by: Michal Pikulski <michal.a.pikulski@gmail.com>
Reviewed-on: #44

Assets/Scripts/Levels/LevelSwitch.cs

@@ -13,33 +13,27 @@ namespace Levels
     /// <summary>
     /// Handles level switching when interacted with. Applies switch data and triggers scene transitions.
     /// </summary>
-    public class LevelSwitch : MonoBehaviour
+    public class LevelSwitch : InteractableBase
     {
         /// <summary>
         /// Data for this level switch (target scene, icon, etc).
         /// </summary>
         public LevelSwitchData switchData;
         private SpriteRenderer _iconRenderer;
-        private Interactable _interactable;
     
         // Settings reference
         private IInteractionSettings _interactionSettings;
 
-        private bool _isActive = true;
+        private bool switchActive = true;
 
         /// <summary>
         /// Unity Awake callback. Sets up icon, interactable, and event handlers.
         /// </summary>
         void Awake()
         {
-            _isActive = true;
+            switchActive = true;
             if (_iconRenderer == null)
                 _iconRenderer = GetComponent<SpriteRenderer>();
-            _interactable = GetComponent<Interactable>();
-            if (_interactable != null)
-            {
-                _interactable.characterArrived.AddListener(OnCharacterArrived);
-            }
         
             // Initialize settings reference
             _interactionSettings = GameManager.GetSettingsObject<IInteractionSettings>();
@@ -47,17 +41,6 @@ namespace Levels
             ApplySwitchData();
         }
 
-        /// <summary>
-        /// Unity OnDestroy callback. Cleans up event handlers.
-        /// </summary>
-        void OnDestroy()
-        {
-            if (_interactable != null)
-            {
-                _interactable.characterArrived.RemoveListener(OnCharacterArrived);
-            }
-        }
-
 #if UNITY_EDITOR
         /// <summary>
         /// Unity OnValidate callback. Ensures icon and data are up to date in editor.
@@ -87,9 +70,9 @@ namespace Levels
         /// <summary>
         /// Handles the start of an interaction (shows confirmation menu and switches the level if confirmed).
         /// </summary>
-        private void OnCharacterArrived()
+        protected override void OnCharacterArrived()
         {
-            if (switchData == null || string.IsNullOrEmpty(switchData.targetLevelSceneName) || !_isActive)
+            if (switchData == null || string.IsNullOrEmpty(switchData.targetLevelSceneName) || !switchActive)
                 return;
 
             var menuPrefab = _interactionSettings?.LevelSwitchMenuPrefab;
@@ -109,7 +92,7 @@ namespace Levels
             }
             // Setup menu with data and callbacks
             menu.Setup(switchData, OnLevelSelectedWrapper, OnMinigameSelected, OnMenuCancel, OnRestartSelected);
-            _isActive = false; // Prevent re-triggering until menu is closed
+            switchActive = false; // Prevent re-triggering until menu is closed
         
             // Switch input mode to UI only
             InputManager.Instance.SetInputMode(InputMode.UI);
@@ -140,7 +123,7 @@ namespace Levels
 
         private void OnMenuCancel()
         {
-            _isActive = true; // Allow interaction again if cancelled
+            switchActive = true; // Allow interaction again if cancelled
             InputManager.Instance.SetInputMode(InputMode.GameAndUI);
         }
     }