feat(library): add ordered backlog page and up-next dashboard tile

src/components/AppHeader.jsx

@@ -29,8 +29,8 @@ import {expireSession, markSession} from '../utils/auth.js';
 
 const NAV_ITEMS = [
     {to: '/dashboard', labelKey: 'NAV.DASHBOARD', Icon: LayoutDashboard},
-    // The wishlist is a tab of the library.
-    {to: '/library', labelKey: 'NAV.LIBRARY', Icon: Library, alsoActiveOn: ['/wishlist']},
+    // The wishlist and the backlog order are tabs of the library.
+    {to: '/library', labelKey: 'NAV.LIBRARY', Icon: Library, alsoActiveOn: ['/wishlist', '/backlog']},
     {to: '/play-next', labelKey: 'NAV.PLAY_NEXT', Icon: Dices},
     {to: '/stats', labelKey: 'NAV.STATS', Icon: ChartColumn},
 ];