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/pages/SetupPage.jsx

@@ -1,4 +1,5 @@
 import { useApp } from '../context/AppContext.js';
+import ProjectHeader from '../components/ProjectHeader.jsx';
 import { useAvailableTranslations } from '../hooks/useAvailableTranslations.js';
 import { bookOptions, formatChunkReference } from '../utils/bibleUtils.jsx';
 
@@ -81,7 +82,6 @@ function SetupForm({ setup, availableTranslations, titleEdited, loadingChapter,
 
 export default function SetupPage() {
   const {
-    headerButtons,
     project,
     setup,
     titleEdited, setTitleEdited,
@@ -125,7 +125,7 @@ export default function SetupPage() {
               {project ? project.title : 'New Study'}
             </h1>
           </div>
-          {headerButtons}
+          <ProjectHeader loading={loadingChapter} />
         </div>
       </header>