feat: enhance layer mask handling and opacity management

- Introduced `getLayerMask` utility to streamline layer mask retrieval.
- Updated layer rendering logic to incorporate layer masks and opacity adjustments.
- Added functionality to prevent dropping a group into its descendants.
- Enhanced image texture rendering to support opacity parameters across various rendering functions.
- Implemented group layer bounds application for better scaling and positioning.
- Added tests to ensure correct behavior when handling layer masks and group layers.
- Created new types for asset generation provenance to track generated assets more effectively.

core/asset.ts

@@ -1,5 +1,6 @@
 import type { Size } from "./geometry";
 import type { AssetId } from "./id";
+import type { AssetProvenance } from "./asset-provenance";
 
 export type Asset = {
   id: AssetId;
@@ -7,4 +8,5 @@ export type Asset = {
   mimeType: string;
   source: string;
   intrinsicSize: Size;
+  provenance?: AssetProvenance;
 };