Fix DataCloneError by excluding non-serializable cache from state

Excluded blendedImageCache and blendedImageDirty properties from layer serialization in CanvasState.ts to prevent DataCloneError when saving state. This ensures that only serializable data is sent to Web Workers, while runtime caches are regenerated as needed. Blend area performance optimization remains functional without serialization issues.

src/types.ts

@@ -28,6 +28,8 @@ export interface Layer {
         width: number;          // szerokość widocznego obszaru
         height: number;         // wysokość widocznego obszaru
     };
+    blendedImageCache?: HTMLCanvasElement; // Cache for the pre-rendered blendArea effect
+    blendedImageDirty?: boolean; // Flag to invalidate the cache
 }
 
 export interface ComfyNode {