Add About & Privacy and Donate modals (M6, §01)

src/app/components/DonateModal.test.tsx

@@ -0,0 +1,46 @@
+import { afterEach, beforeEach, describe, expect, test } from 'vitest';
+import { act } from 'react';
+import { createRoot, type Root } from 'react-dom/client';
+import { DonateModal } from './DonateModal';
+
+(globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+
+let container: HTMLDivElement;
+let root: Root;
+
+beforeEach(() => {
+  container = document.createElement('div');
+  document.body.appendChild(container);
+  root = createRoot(container);
+  act(() => root.render(<DonateModal />));
+});
+
+afterEach(() => {
+  act(() => root.unmount());
+  container.remove();
+});
+
+describe('DonateModal', () => {
+  test('renders a sincere message referencing the project', () => {
+    const text = container.textContent ?? '';
+    expect(text).toMatch(/astrolabe/i);
+    // Some mention of contribution / support
+    expect(text).toMatch(/contribut|support/i);
+  });
+
+  test('renders exactly one primary CTA link', () => {
+    const links = container.querySelectorAll('a');
+    expect(links).toHaveLength(1);
+  });
+
+  test('the CTA link opens in a new tab with rel noopener', () => {
+    const link = container.querySelector('a')!;
+    expect(link.getAttribute('target')).toBe('_blank');
+    expect(link.getAttribute('rel')).toContain('noopener');
+  });
+
+  test('the CTA link has visible text (not icon-only)', () => {
+    const link = container.querySelector('a')!;
+    expect((link.textContent ?? '').trim().length).toBeGreaterThan(0);
+  });
+});