feat: implement inpainting functionality with mask handling

- Added `createMaskedPixelReplacementSource` function to handle pixel replacement using inpainting.
- Introduced `buildInpaintBundle` to prepare inpainting data including mask generation and validation.
- Created utility functions for mask operations such as `applyMaskedContentModeToRgba`, `expandRectWithinBounds`, and others for mask manipulation.
- Developed tests for inpainting preparation and mask raster utilities to ensure functionality and correctness.
- Implemented mask raster operations including inversion, feathering, blurring, and more.

commands/document.test.ts

@@ -8,6 +8,7 @@ import {
   documentAddImageLayerCommand,
   documentAddLayerMaskCommand,
   documentAddRasterLayerCommand,
+  documentApplyLayerMaskOperationCommand,
   documentGroupLayersCommand,
   documentMoveLayerCommand,
   documentRemoveArtboardCommand,
@@ -236,6 +237,30 @@ describe("document commands", () => {
     expect(unmasked.editor.maskEdit).toBeUndefined();
   });
 
+  test("applies operations only to attached layer mask assets", () => {
+    const state = documentAddLayerMaskCommand.execute(
+      { state: documentWithLayers([raster("target", "Target"), raster("loose", "Loose", "loose-asset")]) },
+      { layerId: "target", asset: maskAsset(), maskLayer: raster("mask", "Target Mask", "mask-asset") },
+    );
+    const withLooseAsset = documentAddAssetCommand.execute(
+      { state },
+      { asset: { id: "loose-asset", name: "Loose", mimeType: "image/png", source: "loose-source", intrinsicSize: { w: 100, h: 100 } } },
+    );
+
+    const updated = documentApplyLayerMaskOperationCommand.execute(
+      { state: withLooseAsset },
+      { maskLayerId: "mask", source: "updated-mask", mimeType: "image/png", operation: { type: "invert" } },
+    );
+    const ignored = documentApplyLayerMaskOperationCommand.execute(
+      { state: updated },
+      { maskLayerId: "loose", source: "wrong", operation: { type: "invert" } },
+    );
+
+    expect(updated.document.assets.find((asset) => asset.id === "mask-asset")?.source).toBe("updated-mask");
+    expect(updated.document.assets.find((asset) => asset.id === "mask-asset")?.mimeType).toBe("image/png");
+    expect(ignored.document.assets.find((asset) => asset.id === "loose-asset")?.source).toBe("loose-source");
+  });
+
   test("cleans mask references when deleting targets or mask layers", () => {
     const state = documentAddLayerMaskCommand.execute(
       { state: documentWithLayers([raster("target", "Target")]) },