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/StudyPage.jsx

@@ -1,11 +1,12 @@
 import { createPortal } from 'react-dom';
 import DOMPurify from 'dompurify';
 import { useApp } from '../context/AppContext.js';
+import { buildGreekDefinitionHtml, externalLookupLinks, speakOriginalWord } from '../utils/wordStudy.js';
+import ProjectHeader from '../components/ProjectHeader.jsx';
 import { STUDY_TABS, COMMENTARY_OPTIONS, NT_BOOK_NUMBER, formatChunkReference, CrossRefChip } from '../utils/bibleUtils.jsx';
 
 export default function StudyPage() {
   const {
-    headerButtons,
     project,
     allChunks,
     selectedChunk,
@@ -50,9 +51,6 @@ export default function StudyPage() {
     suggestGreekWordsForChunk,
     suggestHebrewWordsForChunk,
     confirmSuggestWords,
-    speakOriginalWord,
-    externalLookupLinks,
-    buildGreekDefinitionHtml,
     loadVerseText,
     importFinalScriptDocx,
     formatChunkReference: _ignored,
@@ -71,7 +69,7 @@ export default function StudyPage() {
               </p>
             )}
           </div>
-          {headerButtons}
+          <ProjectHeader />
         </div>
       </header>