feat: add sheet component and docs qa baseline

packages/ui/src/components/button.test.tsx

@@ -3,6 +3,7 @@ import userEvent from "@testing-library/user-event";
 import { describe, expect, it, vi } from "vitest";
 
 import { Button } from "./button";
+import { setReducedMotionPreference } from "../test/a11y";
 
 describe("Button", () => {
   it("renders a native button with root and label slots", () => {
@@ -49,4 +50,16 @@ describe("Button", () => {
     expect(link).toHaveAttribute("data-variant", "ghost");
     expect(link).not.toHaveAttribute("type");
   });
+
+  it("preserves the loading contract when reduced motion is preferred", () => {
+    setReducedMotionPreference(true);
+
+    render(<Button loading>Saving</Button>);
+
+    const button = screen.getByRole("button", { name: "Saving" });
+
+    expect(button).toBeDisabled();
+    expect(button).toHaveAttribute("data-loading", "");
+    expect(button.querySelector('[data-slot="icon"]')).toBeInTheDocument();
+  });
 });