Store: Smashwords as a family-filtered book source; free audiobooks stream through the hub; extensions and Sites on Home

- Smashwords: free EPUBs from its shelf feed, filtered (adult/erotica flags, LGBTQ+, keywords, unlabelled romance); admin saves a Smashwords sign-in (encrypted) used to download
- LibriVox chapter audio is fetched and streamed by the hub (with seeking) instead of redirecting the browser to archive.org
- Home: a My apps section with installed extensions and Sites, also in the command palette

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

public/app.js

@@ -353,7 +353,8 @@ function viewHome() {
         ${recents.length && allowed('files') ? `<h2>Recent files</h2><div class="list">${recents.map((r, i) => `<button class="row" data-r="${i}"><span class="ic" style="background:${OFFICE_EXT.has(ext(r.name)) ? '#e0742b' : '#6a7280'}">${icon('file')}</span><span class="grow"><b>${esc(r.name)}</b><small>${esc(r.path.slice(0, r.path.lastIndexOf('/')) || '/')}</small></span></button>`).join('')}</div>` : ''}</div>
     </div>
     ${evening ? '' : '<div id="resume"></div>'}
-    <div class="homeapps">${homeApps()}</div></div>`;
+    <div class="homeapps">${homeApps()}</div><div id="homeext"></div></div>`;
+  if (typeof stHomeExt === 'function' && allowed('store')) stHomeExt($('#homeext'));
   if (typeof homeResume === 'function') homeResume($('#resume'));
   renderNpCard(); // the live Now Playing card (it follows the song and has the controls)
   $('#view').querySelectorAll('button[data-r]').forEach(b => b.onclick = () => {