feat(renderer): add shadcn Toaster primitive

tests/component/ui/sonner.test.tsx

@@ -0,0 +1,17 @@
+import { describe, it, expect } from 'vitest';
+import { render } from '@testing-library/react';
+import { Toaster } from '@/components/ui/sonner';
+import { ThemeProvider } from '@/components/theme-provider';
+
+describe('Toaster', () => {
+  it('renders inside ThemeProvider without crashing', () => {
+    const { container } = render(
+      <ThemeProvider defaultTheme="light" attribute="class">
+        <Toaster />
+      </ThemeProvider>
+    );
+    // The Toaster portal is mounted at body level, so the container may be empty
+    // but the test should not throw
+    expect(container).toBeDefined();
+  });
+});