Allow parent to add comments on submitted documents

Switch admin doc viewer from view mode to comment-only mode so the
parent can annotate student work without editing the text.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/admin.html

@@ -793,6 +793,6 @@
     </div>
   </div>
 
-  <script src="admin.js?v=3"></script>
+  <script src="admin.js?v=4"></script>
 </body>
 </html>