feat: add non-destructive adjustment layers

platform/browser/adjustment.test.ts

@@ -0,0 +1,10 @@
+import { describe, expect, test } from "bun:test";
+import { adjustPixel } from "./exportArtboardPng";
+import { neutralColorAdjustment } from "@core/adjustment-layer";
+
+describe("adjustment pixel calculation", () => {
+  test("neutral adjustment is stable", () => expect(adjustPixel([20, 100, 220], neutralColorAdjustment)).toEqual([20, 100, 220]));
+  test("brightness, contrast, saturation and balance use deterministic ordering", () => {
+    expect(adjustPixel([100, 120, 140], { brightness: .1, contrast: .2, saturation: -.5, colorBalance: { red: .1, green: 0, blue: -.1 } })).toEqual([153, 150, 146]);
+  });
+});