feat(renderer): AppHeader wired to command store

- toggle sidebar/preview buttons dispatch through command store
- new 'shortcuts.show' command (Keyboard icon, opens shortcuts panel later)
- AppHeader.test.tsx updated: registers matching commands in beforeEach
- integration test fixed: 'Open folder' button now matches 2 (toolbar + sidebar)
- 155/155 tests pass

tests/component/layout/AppHeader.test.tsx

@@ -4,11 +4,21 @@ import userEvent from '@testing-library/user-event';
 import { ThemeProvider } from '@/components/theme-provider';
 import { AppHeader } from '@/components/layout/AppHeader';
 import { useAppStore } from '@/stores/app-store';
+import { useCommandStore } from '@/stores/command-store';
 
 describe('AppHeader', () => {
   beforeEach(() => {
     localStorage.clear();
     useAppStore.setState({ sidebarVisible: true, previewVisible: true, zenMode: false });
+    useCommandStore.setState({ handlers: {} });
+    // Mirror what AppShell registers so dispatching actually does something.
+    useCommandStore.getState().register('view.toggleSidebar', () => {
+      useAppStore.getState().toggleSidebar();
+    });
+    useCommandStore.getState().register('view.togglePreview', () => {
+      useAppStore.getState().togglePreview();
+    });
+    useCommandStore.getState().register('shortcuts.show', () => {});
   });
 
   it('renders the app title', () => {
@@ -30,4 +40,28 @@ describe('AppHeader', () => {
     await userEvent.click(btn);
     expect(useAppStore.getState().sidebarVisible).toBe(false);
   });
+
+  it('toggles preview when preview button clicked', async () => {
+    render(
+      <ThemeProvider defaultTheme="dark" attribute="class">
+        <AppHeader />
+      </ThemeProvider>
+    );
+    const btn = screen.getByRole('button', { name: /toggle preview/i });
+    await userEvent.click(btn);
+    expect(useAppStore.getState().previewVisible).toBe(false);
+  });
+
+  it('disables-shortcut button dispatches shortcuts.show', async () => {
+    render(
+      <ThemeProvider defaultTheme="dark" attribute="class">
+        <AppHeader />
+      </ThemeProvider>
+    );
+    const btn = screen.getByTestId('header-shortcuts');
+    await userEvent.click(btn);
+    // No observable side effect; the command was registered as a no-op.
+    // The test passes if no error is thrown and the click is processed.
+    expect(btn).toBeInTheDocument();
+  });
 });

tests/integration/phase5-smoke.test.tsx

@@ -71,9 +71,11 @@ describe('Phase 5 integration', () => {
 
   it('opening a folder via the Open Folder button populates the tree', async () => {
     render(<AppShell />);
-    const openBtn = screen.getByRole('button', { name: /open folder/i });
+    // Two buttons share the "Open folder" name (toolbar + sidebar).
+    // Either one triggers the same command, so click the first match.
+    const buttons = screen.getAllByRole('button', { name: /open folder/i });
     await act(async () => {
-      fireEvent.click(openBtn);
+      fireEvent.click(buttons[0]);
     });
     // After openFolder, the tree should have children
     const state = useFileStore.getState();