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/ReaderPage.jsx

@@ -1,5 +1,7 @@
 import { useState, useEffect, useRef, useMemo, useDeferredValue } from 'react';
 import { useApp } from '../context/AppContext.js';
+import { formatCrossRef, speakOriginalWord } from '../utils/wordStudy.js';
+import AuthStatus from '../components/AuthStatus.jsx';
 import { bookOptions, BookmarkIcon, CopyIcon } from '../utils/bibleUtils.jsx';
 import DrawCanvas from './DrawCanvas.jsx';
 
@@ -7,7 +9,6 @@ const NO_STROKES = []; // stable fallback so DrawCanvas doesn't redraw every ren
 
 export default function ReaderPage() {
   const {
-    authStatus,
     goHome,
     readerBookAbbrev,
     readerChapter, setReaderChapter,
@@ -41,9 +42,7 @@ export default function ReaderPage() {
     handlePlayReaderAudio,
     handleToggleReaderAudioPause,
     handleStopBookAudio,
-    speakOriginalWord,
     copyVerse,
-    formatCrossRef,
     setReaderCrossRefs,
     readerInkByPage,
     updateReaderPageInk,
@@ -270,7 +269,7 @@ export default function ReaderPage() {
             >
               ← Back to Studies
             </button>
-            {authStatus}
+            <AuthStatus />
           </div>
         </div>
       </header>