feat(desktop): add offline cache and verified app updates

Clean release notes in Android and desktop update dialogs. Persist downloaded audio and offline playback events per server and user; add desktop update checks, checksum verification and installer launch.

apps/web/src/widgets/AppShell.tsx

@@ -37,6 +37,7 @@ import { Ambient } from './Ambient';
 import { PlayerBar } from './PlayerBar';
 import { SearchBox } from './SearchBox';
 import s from './AppShell.module.css';
+import { DesktopUpdateDialog, DesktopOfflineBanner } from '../features/desktop/DesktopFeatures';
 
 type NavPath =
   | '/'
@@ -49,6 +50,7 @@ type NavPath =
   | '/uploads/mine'
   | '/admin/settings'
   | '/collection/playlists'
+  | '/collection/downloads'
   | '/collection/history'
   | '/collection/likes'
   | '/collection/dislikes';
@@ -147,6 +149,7 @@ function NavSection({
 export function AppShell() {
   return useAuthState().status === 'signed_in' ? (
     <PlayerProvider>
+      <DesktopUpdateDialog />
       <Shell />
     </PlayerProvider>
   ) : null;
@@ -174,6 +177,7 @@ function Shell() {
         <NavLink to="/" label={t('nav.home')} icon={homeIcon} activeIcon={homeFillIcon} />
         <NavSection mobile={mobile} id="collection" title={t('nav.collection')}>
           <NavLink to="/collection/playlists" label={t('playlists.title')} icon={queueIcon} activeIcon={queueIcon} />
+          {desktop && <NavLink to="/collection/downloads" label={t('desktop.offline')} icon={downloadIcon} activeIcon={downloadIcon} />}
           <NavLink to="/collection/history" label={t('nav.history')} icon={historyIcon} activeIcon={historyFillIcon} />
           <NavLink to="/collection/likes" label={t('nav.likes')} icon={likeIcon} activeIcon={likeFillIcon} count={counts.likes} />
           <NavLink
@@ -298,6 +302,7 @@ function ShellMain() {
   const key = useRouterState({ select: (st) => st.location.pathname });
   return (
     <main id="content" className={s.content} tabIndex={-1}>
+      <DesktopOfflineBanner />
       <div key={key} className={s.routeIn}>
         <Suspense fallback={<PageSkeleton />}>
           <Outlet />