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/layer-mask.ts

@@ -0,0 +1,8 @@
+import type { LayerId } from "./id";
+
+export type LayerMask = {
+  kind: "raster";
+  maskLayerId: LayerId;
+  enabled: boolean;
+  inverted: boolean;
+};