fix: duplicate rows in artist "Top Songs" when a track exists twice in the library

Navidrome can hold the same track twice (downloaded as a single AND as an album track), so
getTopSongs returned two identical rows ("PIXELATED KISSES" x2). Collapse the top-songs list
by title+album for display (keeps the highest play count) on web + Android. SW ns-v59.

Note: this is a display fix — the underlying duplicate files remain a library-cleanup matter.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

android/app/src/main/kotlin/com/novasonic/app/viewmodel/ArtistViewModel.kt

@@ -84,7 +84,9 @@ class ArtistViewModel(app: Application, savedState: SavedStateHandle) : AndroidV
                 val info   = infoDef.await()
 
                 val topDef = async { runCatching { repo.getTopSongs(artist.name) }.getOrDefault(emptyList()) }
-                val top    = topDef.await()
+                // Navidrome can hold the same track twice (single + album track) → duplicate top-song
+                // rows ("PIXELATED KISSES" x2). Collapse by title+album (keeps the highest play count).
+                val top    = topDef.await().distinctBy { "${it.title}|${it.album}".lowercase() }
 
                 _state.value = ArtistUiState(
                     artist = artist, info = info, topSongs = top,