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/palette.js

@@ -54,6 +54,7 @@ function openPalette() {
     const out = navTabs().flatMap(t => MERGED[t[0]] ? MERGED[t[0]][1].filter(allowed).map(id => [id, tabLabel(id)]) : [t]).map(([id, label]) => ({ label: 'Go to ' + label, hint: (navGroups().find(g => g.tabs.some(t => t[0] === (leafOf(id) || id))) || {}).label || 'Page', ic: TAB_ICON[id], run: go('#/' + id), kw: label }));
     if (phone.matches) out.push({ label: 'Edit the bottom bar', hint: 'View', ic: 'menu', run: () => openPinsSheet(), kw: 'menu tabs pins more' });
     if (allowed('tasks') && allowed('calendar')) out.push({ label: 'Go to Tasks', hint: 'Planner', ic: 'check', run: go('#/tasks'), kw: 'todo' }, { label: 'Go to Calendar', hint: 'Planner', ic: 'cal', run: go('#/calendar'), kw: 'agenda events' });
+    if (typeof stItems !== 'undefined' && allowed('store')) for (const i of stItems) { if (i.kind === 'extension' && stInstalled.includes(i.id)) out.push({ label: 'Open ' + i.title, hint: 'Extension', ic: 'cog', run: go('#/store/ext/' + i.id), kw: 'app extension ' + i.title.toLowerCase() }); else if (i.kind === 'link') out.push({ label: 'Open ' + i.title, hint: 'Site', ic: 'link', run: i.embed ? go('#/store/site/' + i.id) : () => window.open(i.url, '_blank', 'noopener,noreferrer'), kw: 'app site ' + i.title.toLowerCase() }); }
     if (allowed('tasks')) out.push({ label: 'New task', hint: 'Create', ic: 'plus', run: () => quickAdd(), kw: 'add todo' });
     if (allowed('calendar')) out.push({ label: 'New event', hint: 'Create', ic: 'plus', run: () => newEvent(ymd(new Date())), kw: 'add calendar' });
     if (allowed('mail') && cfg.mail) out.push({ label: 'New email', hint: 'Create', ic: 'mail', run: () => { location.hash = '#/mail'; setTimeout(() => mailCompose(), 300); }, kw: 'compose write message' });