fix(gallery): restore the download CTA under headerStyle "none"

The report asked whether this was intentional. It is collateral damage from
the #386 swap, not intent.

There are two header download affordances. GalleryView sets
showDownloadAll={false} unconditionally -- "replaced by the new
showHeaderDownload (#386)" -- and passes showHeaderDownload={allowDownloads}.
GalleryLayout renders HeaderDownloadButton in the standard, minimal and hero
branches, but the isNoHeader branch only ever had the now-dead showDownloadAll
button. Net effect: zero download CTA on headerStyle 'none'.

The comment claiming intent -- "Intentionally NOT shown in the no-header
variant where the gallery is fully chromeless by design" -- is factually wrong
about its own branch: isNoHeader renders the menu button, headerExtra (upload
button, countdown timer) and logout. It is a functional-controls bar, not
chromeless. The sentence predates the #386 swap, when showDownloadAll still
gave that bar a download button.

Renders HeaderDownloadButton in that branch in the same slot order as the
other three; it is icon-only below sm, so it fits the compact bar. Removed the
two now-false comments.

Beta themes are unaffected: gallery-premium and gallery-story return from an
earlier branch that never mounts GalleryLayout and get download-all via their
own onDownloadEverything prop, so there is no double CTA.

Refs testplan REPORT.md, headerStyle:none download-CTA warning.

frontend/src/components/gallery/GalleryLayout.tsx

@@ -506,8 +506,7 @@ export const GalleryLayout: React.FC<GalleryLayoutProps> = ({
                 )}
                 {/* Accent Download CTA — also rendered in the minimal header
                     so the action stays one click away regardless of header
-                    style. Intentionally NOT shown in the no-header variant
-                    where the gallery is fully chromeless by design. */}
+                    style. */}
                 {showHeaderDownload && onHeaderDownload && (
                   <HeaderDownloadButton
                     onClick={onHeaderDownload}
@@ -552,6 +551,17 @@ export const GalleryLayout: React.FC<GalleryLayoutProps> = ({
                     <span className="hidden sm:inline">{t('gallery.downloadAll')}</span>
                   </Button>
                 )}
+                {/* Accent Download CTA — 'none' suppresses the *title* header,
+                    not the download affordance: this bar still renders the
+                    menu, headerExtra and logout, so leaving the CTA out just
+                    stranded guests with per-tile downloads only (QA P4-B.05). */}
+                {showHeaderDownload && onHeaderDownload && (
+                  <HeaderDownloadButton
+                    onClick={onHeaderDownload}
+                    isDownloading={isDownloading}
+                    label={t('gallery.download', 'Download')}
+                  />
+                )}
                 {showLogout && onLogout && (
                   <Button
                     variant="outline"
@@ -596,9 +606,7 @@ export const GalleryLayout: React.FC<GalleryLayoutProps> = ({
                 )}
 
                 {/* Accent Download CTA — also rendered above the hero so the
-                    primary download action is reachable without scrolling.
-                    Intentionally NOT shown in the no-header variant where
-                    the gallery is fully chromeless by design. */}
+                    primary download action is reachable without scrolling. */}
                 {showHeaderDownload && onHeaderDownload && (
                   <HeaderDownloadButton
                     onClick={onHeaderDownload}

frontend/src/components/gallery/__tests__/GalleryLayout.downloadCta.test.tsx

@@ -0,0 +1,97 @@
+/**
+ * The download CTA must survive every header style.
+ *
+ * `showDownloadAll` (the old primary "Download all" button) is hard-wired to
+ * false by GalleryView — the live entry point is `showHeaderDownload`, the
+ * accent CTA that opens the resolution picker. That CTA was rendered in the
+ * standard, minimal and hero headers but not in `headerStyle: 'none'`, whose
+ * comment claimed the variant was "fully chromeless by design" — it is not: it
+ * still renders the menu, headerExtra and logout. So `none` silently dropped
+ * the gallery's primary download affordance, leaving guests with per-tile
+ * downloads and the selection-mode bulk button only (QA P4-B.05).
+ *
+ * 'none' means "no title header", not "no downloads".
+ */
+import { render, screen } from '@testing-library/react';
+import { describe, expect, it, vi } from 'vitest';
+import { MemoryRouter } from 'react-router-dom';
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import type { HeaderStyleType } from '../../../types/theme.types';
+
+import { GalleryLayout } from '../GalleryLayout';
+
+vi.mock('react-i18next', async () => {
+  const actual = await vi.importActual<typeof import('react-i18next')>('react-i18next');
+  return {
+    ...actual,
+    useTranslation: () => ({
+      t: (key: string, second?: any) => (typeof second === 'string' ? second : key),
+      i18n: { language: 'en' },
+    }),
+  };
+});
+
+vi.mock('../../../contexts/ThemeContext', async () => {
+  const actual = await vi.importActual<typeof import('../../../contexts/ThemeContext')>(
+    '../../../contexts/ThemeContext'
+  );
+  return { ...actual, useTheme: () => ({ theme: {} }) };
+});
+
+vi.mock('../../../services/cms.service', () => ({
+  cmsService: { getPublicPage: vi.fn().mockRejectedValue(new Error('no cms')) },
+}));
+
+const renderLayout = (headerStyle: HeaderStyleType) => {
+  const queryClient = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+  return render(
+    <QueryClientProvider client={queryClient}>
+      <MemoryRouter>
+        <GalleryLayout
+          event={{ event_name: 'ZZTEST Wedding' }}
+          headerStyle={headerStyle}
+          showDownloadAll={false}
+          onDownloadAll={vi.fn()}
+          showHeaderDownload
+          onHeaderDownload={vi.fn()}
+          showLogout
+          onLogout={vi.fn()}
+        >
+          <div>photos</div>
+        </GalleryLayout>
+      </MemoryRouter>
+    </QueryClientProvider>
+  );
+};
+
+describe('GalleryLayout header download CTA', () => {
+  it.each<HeaderStyleType>(['standard', 'minimal', 'hero', 'none', 'banner'])(
+    'renders the download CTA with headerStyle "%s"',
+    (headerStyle) => {
+      const { unmount } = renderLayout(headerStyle);
+      expect(screen.getAllByRole('button', { name: 'Download' }).length).toBeGreaterThan(0);
+      unmount();
+    }
+  );
+
+  it('omits the CTA when the gallery does not allow downloads', () => {
+    const queryClient = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+    render(
+      <QueryClientProvider client={queryClient}>
+        <MemoryRouter>
+          <GalleryLayout
+            event={{ event_name: 'ZZTEST Wedding' }}
+            headerStyle="none"
+            showDownloadAll={false}
+            showHeaderDownload={false}
+            showLogout
+            onLogout={vi.fn()}
+          >
+            <div>photos</div>
+          </GalleryLayout>
+        </MemoryRouter>
+      </QueryClientProvider>
+    );
+    expect(screen.queryByRole('button', { name: 'Download' })).not.toBeInTheDocument();
+  });
+});