feat: add generation cancel job functionality and improve job handling

- Introduced `generationCancelJob` command ID in `commands/ids.ts`.
- Added `GenerationCancelJobPayload` type in `commands/payloads.ts`.
- Enhanced job status to include "cancelled" in `editor/state.ts`.
- Updated `runGenerationJob` to accept an `AbortSignal` and handle cancellation.
- Implemented cancellation logic in `runGenerate` and related functions.
- Added tests for job cancellation in `operations/generation/workflow.test.ts`.
- Improved layer rendering logic to prevent stack overflow in `editor/document-indexes.ts`.
- Added raster size assertions in `platform/browser/rasterLimits.ts` for image processing limits.
- Enhanced image file handling to check for size limits in `platform/browser/imageFiles.ts`.
- Updated UI components to reflect job cancellation state in `view/GenerationJobStatus.tsx` and `view/bottom-controls/GenerateActionControls.tsx`.

platform/browser/maskRaster.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test";
-import { cropMaskValuesToRgba, expandRectWithinBounds, invertMaskValues } from "./maskRaster";
+import { blurMaskValues, cropMaskValuesToRgba, dilateMaskValues, erodeMaskValues, expandRectWithinBounds, invertMaskValues } from "./maskRaster";
 
 describe("mask raster utilities", () => {
   test("exports the normalized drawn mask without filling the whole crop", () => {
@@ -28,6 +28,13 @@ describe("mask raster utilities", () => {
       h: 64,
     });
   });
+
+  test("uses separable mask kernels without changing square-kernel semantics", () => {
+    const values = new Uint8ClampedArray([0, 0, 0, 0, 255, 0, 0, 0, 0]);
+    expect([...dilateMaskValues(values, 3, 3, 1)]).toEqual(new Array(9).fill(255));
+    expect([...erodeMaskValues(new Uint8ClampedArray(new Array(9).fill(255)), 3, 3, 1)]).toEqual(new Array(9).fill(255));
+    expect([...blurMaskValues(values, 3, 3, 1)]).toEqual(new Array(9).fill(28));
+  });
 });
 
 function activeRedPixels(rgba: Uint8ClampedArray) {