feat(renderer): add shadcn textarea primitive

tests/component/ui/textarea.test.tsx

@@ -0,0 +1,12 @@
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { Textarea } from '@/components/ui/textarea';
+
+describe('Textarea', () => {
+  it('renders a multi-line input', () => {
+    render(<Textarea aria-label="notes" defaultValue="hello" />);
+    const ta = screen.getByLabelText(/notes/i);
+    expect(ta.tagName).toBe('TEXTAREA');
+    expect(ta).toHaveValue('hello');
+  });
+});