Extract project header, share link, exports, and auth status

- ProjectHeader component replaces the headerButtons JSX in context; it
  owns the export menu and share panel state.
- useShareLink (share status/enable/revoke/copy) and useSharedView
  (?share= read-only view, now used directly by the router).
- utils/projectExport: HTML/Markdown/DOCX download and print-to-PDF.
- AuthStatus component replaces the authStatus JSX in context.
- Pages import wordStudy helpers directly instead of via context.
- Remove dead copyPronunciationGuide (PronunciationPage has its own).
- Tests: Markdown export, enabling a share link, the ?share= view.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/App.test.jsx

@@ -80,7 +80,8 @@ async function loadChapter() {
   const user = userEvent.setup();
   await renderApp();
   await user.click(screen.getAllByRole('button', { name: /new project/i })[0]);
-  await user.click(screen.getByRole('button', { name: /load chapter/i }));
+  // SetupPage is lazy-loaded, so wait for it on first open
+  await user.click(await screen.findByRole('button', { name: /load chapter/i }));
   await screen.findByText(/Scripture & Chunks/i);
   return user;
 }
@@ -586,3 +587,47 @@ describe('Home page', () => {
     await waitFor(() => expect(JSON.parse(localStorage.getItem('readingPlan'))?.bookAbbrev).toBe('GEN'));
   });
 });
+
+// ---------------------------------------------------------------------------
+// Project header (ProjectHeader + useShareLink) and the shared read-only view
+// ---------------------------------------------------------------------------
+describe('Project header and sharing', () => {
+  const json = (status, data) => Promise.resolve({ ok: status < 400, status, json: () => Promise.resolve(data) });
+
+  test('Export → Markdown downloads a file', async () => {
+    const user = await loadChapter();
+    await user.click(screen.getByRole('button', { name: /export/i }));
+    await user.click(screen.getByRole('button', { name: /export markdown/i }));
+    expect(URL.createObjectURL).toHaveBeenCalled();
+  });
+
+  test('enabling sharing shows a copyable link', async () => {
+    const fallback = buildFetchMock();
+    const fetchMock = vi.fn((url, opts = {}) => {
+      if (url.startsWith('/api/projects/') && url.endsWith('/share')) {
+        return (opts.method ?? 'GET') === 'POST' ? json(200, { shareToken: 'tok123' }) : json(200, { shareToken: null });
+      }
+      return fallback(url, opts);
+    });
+    vi.stubGlobal('fetch', fetchMock);
+    const user = await loadChapter();
+    await user.click(screen.getByRole('button', { name: /share/i }));
+    await user.click(screen.getByRole('button', { name: /enable sharing/i }));
+    expect(await screen.findByDisplayValue(/\?share=tok123$/)).toBeInTheDocument();
+  });
+
+  test('a ?share= link shows the read-only view without signing in', async () => {
+    window.history.pushState({}, '', '/?share=abc');
+    const fallback = buildFetchMock();
+    vi.stubGlobal('fetch', vi.fn((url, opts) => (url === '/api/share/abc'
+      ? json(200, { id: 's1', title: 'Shared Titus', translation: 'BSB', chapters: [] })
+      : fallback(url, opts))));
+    try {
+      render(<App />);
+      expect(await screen.findByText(/read-only shared view/i)).toBeInTheDocument();
+      expect(screen.getByTitle('Shared study')).toBeInTheDocument();
+    } finally {
+      window.history.pushState({}, '', '/');
+    }
+  });
+});