feat(renderer): AboutDialog (version + GitHub link)

tests/component/modals/AboutDialog.test.tsx

@@ -0,0 +1,34 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { AboutDialog } from '@/components/modals/AboutDialog';
+import { useAppStore } from '@/stores/app-store';
+
+describe('AboutDialog', () => {
+  beforeEach(() => {
+    window.electronAPI = {
+      app: {
+        getVersion: vi.fn().mockResolvedValue('5.0.0'),
+        openExternal: vi.fn().mockResolvedValue({ ok: true }),
+      },
+    } as any;
+    // Reset store to about modal so dialog renders
+    useAppStore.setState({ modal: { kind: 'about' } } as any);
+  });
+
+  it('renders title and version', async () => {
+    render(<AboutDialog />);
+    expect(screen.getByText(/about markdownconverter/i)).toBeInTheDocument();
+    expect(await screen.findByText(/5\.0\.0/)).toBeInTheDocument();
+  });
+
+  it('closes when the close button is clicked', async () => {
+    render(<AboutDialog />);
+    // dialog-footer has the visible Close button; the X button also has sr-only "Close"
+    const closeButtons = await screen.findAllByRole('button', { name: /close/i });
+    const close = closeButtons[0];
+    await userEvent.click(close);
+    // closeModal sets modal.kind = null, so isOpen=false, Dialog unmounts
+    expect(screen.queryByRole('dialog')).not.toBeInTheDocument();
+  });
+});