feat(core-ui): add jsdom Vitest config + RTL tests for components

Adopts jsdomVitestConfig from @repo/core-typescript. Adds
@testing-library/react, @testing-library/user-event, jsdom devDeps.
Writes smoke + interaction tests for every atom/molecule/organism/template
using renderWithProviders from @repo/core-testing/react.

Components covered:
- atoms: Button (5 tests), Input (4), Label (2)
- molecules: FormField (5)
- organisms / templates: empty barrels, no components

Adjustments:
- core-ui/tsconfig.json now extends react-library.json (jsx: react-jsx)
  with rootDir "." + paths {"@/*"} + types [vitest/globals, jest-dom]
- core-typescript/vitest.base.jsdom.ts uses ./vitest.base.node.ts (explicit
  .ts extension) so Node's ESM resolver finds the source file when loaded
  via the package export from a downstream package

Spec: §6.1, §6.5

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/core-ui/src/atoms/button/button.test.tsx

@@ -0,0 +1,42 @@
+import { describe, it, expect, vi } from "vitest";
+import { renderWithProviders } from "@repo/core-testing/react";
+import { screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { Button } from "./button";
+
+describe("Button", () => {
+  it("renders children inside a button", () => {
+    renderWithProviders(<Button>Click me</Button>);
+    expect(screen.getByRole("button", { name: "Click me" })).toBeInTheDocument();
+  });
+
+  it("calls onClick when activated", async () => {
+    const handleClick = vi.fn();
+    renderWithProviders(<Button onClick={handleClick}>Go</Button>);
+    await userEvent.click(screen.getByRole("button", { name: "Go" }));
+    expect(handleClick).toHaveBeenCalledOnce();
+  });
+
+  it("applies the destructive variant class", () => {
+    renderWithProviders(<Button variant="destructive">X</Button>);
+    expect(screen.getByRole("button")).toHaveClass(/destructive/);
+  });
+
+  it("applies the lg size class", () => {
+    renderWithProviders(<Button size="lg">X</Button>);
+    expect(screen.getByRole("button")).toHaveClass(/h-11/);
+  });
+
+  it("disabled prop sets the attribute and prevents click handler", async () => {
+    const handleClick = vi.fn();
+    renderWithProviders(
+      <Button disabled onClick={handleClick}>
+        X
+      </Button>,
+    );
+    const button = screen.getByRole("button");
+    expect(button).toBeDisabled();
+    await userEvent.click(button);
+    expect(handleClick).not.toHaveBeenCalled();
+  });
+});