feat: fans on local Navidrome artists (android) + harmonize web fan layout

- Android local artist page (ArtistDetailScreen/ArtistViewModel) now resolves the Deezer
  artist (fan-sorted, so same-name collisions pick the popular one) and shows "<n> Fans"
  under the name — parity with the web local artist page.
- Also migrated ArtistViewModel's preview to the app-level PreviewController: the local
  artist page had its OWN uncontrollable MediaPlayer preview, which had the same
  "keeps playing after navigating away" bug. Now every preview uses the global bar.
- Web: the artist-hero fan line was laid out in a row next to the name (flex without
  column direction) and used an odd tinted color — now stacked cleanly under the name in
  a muted white. SW ns-v54.
- CHANGELOG: documented the above + added a Known Bug (Android synced-lyrics auto-scroll
  still doesn't follow playback).

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

android/app/src/main/kotlin/com/novasonic/app/ui/screen/ArtistDetailScreen.kt

@@ -43,6 +43,7 @@ import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
 import coil.compose.AsyncImage
 import com.novasonic.app.api.model.Song
+import com.novasonic.app.api.model.fmtFanCount
 import com.novasonic.app.player.PlayerState
 import com.novasonic.app.ui.component.AlbumCard
 import com.novasonic.app.ui.component.ConcertsSheet
@@ -241,13 +242,21 @@ fun ArtistDetailScreen(
                         )
                     )
                 )
-                Text(
-                    artist.name,
-                    fontFamily = Outfit, fontWeight = FontWeight.ExtraBold, fontSize = 30.sp,
-                    letterSpacing = (-0.5).sp, color = Color.White,
-                    maxLines = 2, overflow = TextOverflow.Ellipsis,
-                    modifier = Modifier.align(Alignment.BottomStart).padding(20.dp),
-                )
+                Column(modifier = Modifier.align(Alignment.BottomStart).padding(20.dp)) {
+                    Text(
+                        artist.name,
+                        fontFamily = Outfit, fontWeight = FontWeight.ExtraBold, fontSize = 30.sp,
+                        letterSpacing = (-0.5).sp, color = Color.White,
+                        maxLines = 2, overflow = TextOverflow.Ellipsis,
+                    )
+                    state.fanCount?.takeIf { it > 0 }?.let {
+                        Text(
+                            "${fmtFanCount(it)} Fans",
+                            fontFamily = Outfit, fontWeight = FontWeight.SemiBold, fontSize = 13.sp,
+                            color = Color.White.copy(0.58f), modifier = Modifier.padding(top = 4.dp),
+                        )
+                    }
+                }
             }
             Spacer(Modifier.height(16.dp))
         }

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

@@ -1,7 +1,6 @@
 package com.novasonic.app.viewmodel
 
 import android.app.Application
-import android.media.MediaPlayer
 import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.viewModelScope
@@ -42,6 +41,8 @@ data class ArtistUiState(
     // Concerts
     val events: List<ConcertEvent> = emptyList(),
     val showEventsSheet: Boolean = false,
+    // Deezer fan count of the matched artist (shown under the name), null if unknown
+    val fanCount: Long? = null,
     // Preview + download
     val previewingId: Long? = null,
     val downloadSheetItem: ItunesItem? = null,
@@ -51,22 +52,22 @@ class ArtistViewModel(app: Application, savedState: SavedStateHandle) : AndroidV
 
     private val repo      = app.app.repository
     private val player    = app.app.playerController
+    private val preview   = app.app.previewController
     private val artistId: String? = savedState["artistId"]
 
     private val _state = MutableStateFlow(ArtistUiState())
     val state: StateFlow<ArtistUiState> = _state
 
-    private var mediaPlayer: MediaPlayer? = null
-
     init {
         if (artistId.isNullOrBlank()) {
             _state.value = ArtistUiState(isLoading = false, error = "Keine Künstler-ID übergeben")
         } else {
             load()
         }
+        // Mirror the app-level preview so track rows show which clip plays (bar lives in AppNavigation).
         viewModelScope.launch {
-            player.state.collect { ps ->
-                if (ps.isPlaying && _state.value.previewingId != null) stopPreview()
+            preview.state.collect { ps ->
+                _state.value = _state.value.copy(previewingId = if (ps.isPlaying) ps.trackId else null)
             }
         }
     }
@@ -109,14 +110,18 @@ class ArtistViewModel(app: Application, savedState: SavedStateHandle) : AndroidV
         }.getOrNull()
 
         val artists = searchResp?.results?.filter { it.wrapperType == "artist" } ?: emptyList()
-        val iArtistId = (
+        // artists are sorted by fan count (ItunesClient), so the first name match is the most popular
+        // one — disambiguates same-name artists (5x "Joji").
+        val iArtist = (
             artists.find { it.artistName?.equals(artistName, ignoreCase = true) == true }
                 ?: artists.find {
                     val n = it.artistName ?: return@find false
                     n.contains(artistName, ignoreCase = true) || artistName.contains(n, ignoreCase = true)
                 }
-                ?: artists.firstOrNull() // iTunes sorts by relevance — first hit is almost always right
-        )?.artistId
+                ?: artists.firstOrNull()
+        )
+        val iArtistId = iArtist?.artistId
+        if (iArtist?.fanCount != null) _state.value = _state.value.copy(fanCount = iArtist.fanCount)
 
         if (iArtistId != null) {
             coroutineScope {
@@ -254,41 +259,17 @@ class ArtistViewModel(app: Application, savedState: SavedStateHandle) : AndroidV
         }
     }
 
-    // ── iTunes 30s preview ───────────────────────────────────────────────────
+    // ── 30s preview (app-level PreviewController → global control bar, survives navigation) ──
 
     fun togglePreview(track: ItunesItem) {
         val url = track.previewUrl ?: return
         val id  = track.trackId   ?: return
-        if (_state.value.previewingId == id) stopPreview() else startPreview(url, id)
-    }
-
-    private fun startPreview(url: String, id: Long) {
-        stopPreview()
         player.pause()
-        _state.value = _state.value.copy(previewingId = id)
-        viewModelScope.launch(Dispatchers.IO) {
-            try {
-                val mp = MediaPlayer().apply {
-                    setDataSource(url)
-                    prepare()
-                    start()
-                    setOnCompletionListener { _state.value = _state.value.copy(previewingId = null) }
-                }
-                mediaPlayer = mp
-            } catch (e: Exception) {
-                _state.value = _state.value.copy(previewingId = null)
-            }
-        }
+        preview.toggle(id, url, track.trackName ?: "", track.artistName ?: "", track.artworkUrl100)
     }
 
-    fun stopPreview() {
-        mediaPlayer?.runCatching { stop(); release() }
-        mediaPlayer = null
-        _state.value = _state.value.copy(previewingId = null)
-    }
+    fun stopPreview() = preview.stop()
 
-    override fun onCleared() {
-        super.onCleared()
-        stopPreview()
-    }
+    // No onCleared stopPreview — the preview is app-level so it keeps playing (controllable via the
+    // global bar) after leaving this screen.
 }