feat(most-played): add dedicated Most Played page (#86)

New sidebar item (TrendingUp icon, /most-played route) with:

- Top Artists section: derived by grouping frequent albums by artistId
  and summing playCount — no extra API calls needed. Shows up to 10
  artists as a responsive grid with avatar, rank and total play count.
- Top Albums section: paginated list using getAlbumList('frequent'),
  50 albums per batch with a "Load more" button. Each row shows rank,
  cover thumbnail (44px), album name, artist (navigates to artist
  page), year and play count.
- Sort toggle (most plays first / fewest plays first).

Also adds playCount?: number to SubsonicAlbum — Navidrome returns this
field in getAlbumList2?type=frequent but it was missing from the type.

Closes #86

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/locales/ru.ts

@@ -20,6 +20,7 @@ export const ruTranslation = {
     offlineLibrary: 'Офлайн-библиотека',
     genres: 'Жанры',
     playlists: 'Плейлисты',
+    mostPlayed: 'Часто слушаемое',
     radio: 'Онлайн-радио',
     libraryScope: 'Область медиатеки',
     allLibraries: 'Все библиотеки',
@@ -831,6 +832,16 @@ export const ruTranslation = {
     metaSaved: 'Плейлист сохранён',
     downloadZip: 'Скачать (ZIP)',
   },
+  mostPlayed: {
+    title: 'Часто слушаемое',
+    topArtists: 'Топ исполнителей',
+    topAlbums: 'Топ альбомов',
+    plays: '{{n}} прослушиваний',
+    sortMost: 'Сначала популярные',
+    sortLeast: 'Сначала малоизвестные',
+    loadMore: 'Загрузить больше альбомов',
+    noData: 'Нет данных о прослушиваниях. Начните слушать!',
+  },
   radio: {
     title: 'Онлайн-радио',
     empty: 'Радиостанции не настроены.',