add library filter, drop folders page

src/components/layout/AppHeader.tsx

@@ -33,7 +33,6 @@ const TOP_LEVEL_PATHS = new Set([
   '/',
   '/movies',
   '/shows',
-  '/folders',
   '/playlists',
   '/music',
   '/search',
@@ -45,7 +44,6 @@ function pageTitleFor(pathname: string): string {
   if (pathname === '/') return 'Home'
   if (pathname === '/movies') return 'Movies'
   if (pathname === '/shows') return 'TV Shows'
-  if (pathname === '/folders') return 'Folders'
   if (pathname === '/playlists') return 'Playlists'
   if (pathname === '/music') return 'Music'
   if (pathname === '/search') return 'Search'

src/components/layout/AppShell.tsx

@@ -16,7 +16,6 @@ import {
   Activity,
   Radio,
   Download,
-  Folders,
 } from '../../lib/icons'
 import type { AuthState } from '../../api/types'
 import AppHeader from './AppHeader'
@@ -55,7 +54,6 @@ const NAV_SECTIONS: NavSection[] = [
       { to: '/', icon: Home, label: 'Home' },
       { to: '/movies', icon: Film, label: 'Movies' },
       { to: '/shows', icon: Tv, label: 'Shows' },
-      { to: '/folders', icon: Folders, label: 'Folders' },
       { to: '/playlists', icon: Playlists, label: 'Playlists' },
       { to: '/live', icon: Radio, label: 'Live TV' },
       { to: '/requests', icon: Database, label: 'Requests' },