feat: add removable reference feature vertical slice

tests/component/design-tokens.test.jsx

@@ -3,12 +3,17 @@
 import { render, screen } from "@testing-library/react";
 import { describe, expect, it } from "vitest";
 
-import { DesignTokenShowcase } from "../../src/sample/contract-fixture/design-token-showcase.jsx";
+import { Button } from "../../src/presentation/components/ui/button.jsx";
+import { Card } from "../../src/presentation/components/ui/card.jsx";
 
 describe("design-token fixture", () => {
   it("uses static semantic primitive classes", () => {
-    render(<DesignTokenShowcase />);
-    expect(screen.getByRole("region")).toHaveClass("ui-panel");
+    render(
+      <Card title="Design token fixture">
+        <Button>Token action</Button>
+      </Card>,
+    );
+    expect(screen.getByRole("article")).toHaveClass("ui-card");
     expect(screen.getByRole("button")).toHaveClass("ui-button");
   });
 });