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/fr.ts

@@ -19,6 +19,7 @@ export const frTranslation = {
     offlineLibrary: 'Bibliothèque hors ligne',
     genres: 'Genres',
     playlists: 'Playlists',
+    mostPlayed: 'Les plus joués',
     radio: 'Radio Internet',
     libraryScope: 'Portée de la bibliothèque',
     allLibraries: 'Toutes les bibliothèques',
@@ -777,6 +778,16 @@ export const frTranslation = {
     metaSaved: 'Playlist mise à jour',
     downloadZip: 'Télécharger (ZIP)',
   },
+  mostPlayed: {
+    title: 'Les plus joués',
+    topArtists: 'Artistes populaires',
+    topAlbums: 'Albums populaires',
+    plays: '{{n}} écoutes',
+    sortMost: 'Plus joués en premier',
+    sortLeast: 'Moins joués en premier',
+    loadMore: 'Charger plus d\'albums',
+    noData: 'Aucune donnée d\'écoute. Commencez à écouter !',
+  },
   radio: {
     title: 'Radio Internet',
     empty: 'Aucune station radio configurée.',