feat: enhance WelcomeDialog, export dialogs, GitStatusPanel, add CommandPalette, FindReplaceBar, and new converter dialogs

- WelcomeDialog: add quick start, feature showcase, keyboard shortcuts, recent files, version display
- ExportDocxDialog/ExportHtmlDialog/ExportPdfDialog: add header/footer, paper size, margin controls
- GitStatusPanel: full staging/unstaging, discard, commit workflow
- CommandPalette: fuzzy command search with keyboard navigation
- FindReplaceBar: find/replace with regex, case, whole-word options
- New dialogs: BatchMediaConverterDialog, HeaderFooterDialog, PdfEditorDialog, UniversalConverterDialog
- Tests: comprehensive coverage for all new/updated components

tests/component/modals/ExportHtmlDialog.test.tsx

@@ -15,27 +15,28 @@ vi.mock('@/lib/ipc', () => ({
 
 import { ipc } from '@/lib/ipc';
 
-describe('ExportHtmlDialog', () => {
-  beforeEach(() => {
-    localStorage.clear();
-    vi.clearAllMocks();
-    (ipc.app.showSaveDialog as any).mockImplementation(async (args) => ({
-      ok: true,
-      data: args?.defaultPath ?? '/out.html',
-    }));
-    (ipc.file.writeBuffer as any).mockResolvedValue({ ok: true });
-    useSettingsStore.setState(useSettingsStore.getInitialState());
-    useFileStore.setState({
-      activeTabId: '/test.md',
-      openTabs: [{ id: '/test.md', path: '/test.md', title: 'test.md', dirty: false }],
-    } as any);
-    useEditorStore.setState({
-      buffers: new Map([
-        ['/test.md', { id: '/test.md', path: '/test.md', content: '# hi', dirty: false }],
-      ]),
-    } as any);
-  });
+beforeEach(() => {
+  localStorage.clear();
+  vi.clearAllMocks();
+  (window.electronAPI as any) = {};
+  (ipc.app.showSaveDialog as any).mockImplementation(async (args) => ({
+    ok: true,
+    data: args?.defaultPath ?? '/out.html',
+  }));
+  (ipc.file.writeBuffer as any).mockResolvedValue({ ok: true });
+  useSettingsStore.setState(useSettingsStore.getInitialState());
+  useFileStore.setState({
+    activeTabId: '/test.md',
+    openTabs: [{ id: '/test.md', path: '/test.md', title: 'test.md', dirty: false }],
+  } as any);
+  useEditorStore.setState({
+    buffers: new Map([
+      ['/test.md', { id: '/test.md', path: '/test.md', content: '# hi', dirty: false }],
+    ]),
+  } as any);
+});
 
+describe('ExportHtmlDialog', () => {
   it('renders with default github highlight style', () => {
     render(<ExportHtmlDialog sourcePath="/test.md" />);
     expect(screen.getByText(/export to html/i)).toBeInTheDocument();
@@ -49,9 +50,41 @@ describe('ExportHtmlDialog', () => {
     expect(ipc.file.writeBuffer).toHaveBeenCalledTimes(1);
     const callArg = (ipc.file.writeBuffer as any).mock.calls[0][0];
     expect(callArg.path).toBe('/test.html');
-    // The buffer is a Uint8Array; in JSDOM cross-realm the prototype check
-    // is unreliable, so verify shape instead.
     expect(callArg.buffer).toBeDefined();
     expect(callArg.buffer.length).toBeGreaterThan(0);
   });
+
+  it('shows self-contained toggle', () => {
+    render(<ExportHtmlDialog sourcePath="/test.md" />);
+    expect(screen.getByRole('switch', { name: /self-contained/i })).toBeInTheDocument();
+  });
+
+  it('shows TOC toggle and number sections toggle', () => {
+    render(<ExportHtmlDialog sourcePath="/test.md" />);
+    expect(screen.getByRole('switch', { name: /table of contents/i })).toBeInTheDocument();
+    expect(screen.getByRole('switch', { name: /number sections/i })).toBeInTheDocument();
+  });
+
+  it('shows TOC depth when TOC is enabled', async () => {
+    render(<ExportHtmlDialog sourcePath="/test.md" />);
+    await userEvent.click(screen.getByRole('switch', { name: /table of contents/i }));
+    expect(screen.getByLabelText(/toc depth/i)).toBeInTheDocument();
+  });
+
+  it('shows custom CSS input', () => {
+    render(<ExportHtmlDialog sourcePath="/test.md" />);
+    expect(screen.getByLabelText(/custom css file path/i)).toBeInTheDocument();
+  });
+
+  it('sends options via electronAPI.export.withOptions when available', async () => {
+    const mockWithOptions = vi.fn().mockResolvedValue({ ok: true });
+    (window.electronAPI as any) = {
+      export: { withOptions: mockWithOptions },
+    };
+    render(<ExportHtmlDialog sourcePath="/test.md" />);
+    await userEvent.click(screen.getByRole('button', { name: /^export$/i }));
+    await waitFor(() => expect(mockWithOptions).toHaveBeenCalledWith('html', expect.any(Object)));
+    expect(mockWithOptions.mock.calls[0][1].standalone).toBe(true);
+    expect(mockWithOptions.mock.calls[0][1].selfContained).toBe(false);
+  });
 });