fix(android): show artist images in Apple-Music search (Erkunden)

iTunes artist entities carry no artwork, so search results rendered as bare grey
circles. Mirror the web PWA: after showing results, fetch one album per artist and
borrow its cover (entity=album, limit=1), applied only if the user is still viewing
the same artist set. Also give ArtistCard a Person-icon fallback instead of an empty
grey dot, and fall back to the artist id for Subsonic (library) artist covers.

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

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

@@ -283,7 +283,9 @@ private fun LibrarySearchContent(
                     horizontalArrangement = Arrangement.spacedBy(16.dp),
                 ) {
                     items(artists, key = { it.id }) { a ->
-                        ArtistCard(name = a.name, imageUrl = coverUrl(a.coverArt)) { onArtistClick(a) }
+                        // search3 artist results usually omit coverArt → fall back to the artist
+                        // id, which Navidrome's getCoverArt accepts and resolves to the artist image.
+                        ArtistCard(name = a.name, imageUrl = coverUrl(a.coverArt ?: a.id)) { onArtistClick(a) }
                     }
                 }
                 Spacer(Modifier.height(8.dp))
@@ -597,15 +599,27 @@ private fun ArtistCard(name: String, imageUrl: String?, onClick: () -> Unit) {
             .width(80.dp)
             .clickable(onClick = onClick),
     ) {
-        AsyncImage(
-            model = imageUrl,
-            contentDescription = name,
-            contentScale = ContentScale.Crop,
+        Box(
+            contentAlignment = Alignment.Center,
             modifier = Modifier
                 .size(72.dp)
                 .clip(androidx.compose.foundation.shape.CircleShape)
                 .background(NsSurface2),
-        )
+        ) {
+            if (imageUrl != null) {
+                AsyncImage(
+                    model = imageUrl,
+                    contentDescription = name,
+                    contentScale = ContentScale.Crop,
+                    modifier = Modifier.fillMaxSize(),
+                )
+            } else {
+                Icon(
+                    Icons.Default.Person, contentDescription = null,
+                    tint = NsOnSurface2, modifier = Modifier.size(32.dp),
+                )
+            }
+        }
         Spacer(Modifier.height(6.dp))
         Text(
             name, fontFamily = Outfit, fontSize = 12.sp, fontWeight = FontWeight.Medium,

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

@@ -110,18 +110,46 @@ class ExploreViewModel(app: Application) : AndroidViewModel(app) {
             try {
                 val resp = ItunesClient.search(term)
                 val results = resp.results
+                val artists = results.filter { it.wrapperType == "artist" }
                 _state.value = _state.value.copy(
-                    artists    = results.filter { it.wrapperType == "artist" },
+                    artists    = artists,
                     albums     = results.filter { it.wrapperType == "collection" },
                     tracks     = results.filter { it.wrapperType == "track" && it.kind == "song" },
                     isSearching = false,
                 )
+                enrichArtistArt(artists)
             } catch (e: Exception) {
                 _state.value = _state.value.copy(isSearching = false, error = e.message)
             }
         }
     }
 
+    /**
+     * iTunes artist entities carry no artwork, so search results render as grey circles. Mirror the
+     * web PWA: fetch one album per artist and borrow its cover. Runs after the main results are shown
+     * (list appears instantly) and only applies if the user is still viewing the same artist set.
+     */
+    private fun enrichArtistArt(artists: List<ItunesItem>) {
+        if (artists.none { it.artworkUrl100.isNullOrBlank() && it.artistName != null }) return
+        viewModelScope.launch {
+            val enriched = artists.map { a ->
+                async {
+                    if (!a.artworkUrl100.isNullOrBlank()) return@async a
+                    val name = a.artistName ?: return@async a
+                    val art = runCatching {
+                        ItunesClient.search(name, entity = "album", limit = 1).results
+                            .firstOrNull { it.wrapperType == "collection" }?.artworkUrl100
+                    }.getOrNull()
+                    if (art != null) a.copy(artworkUrl100 = art) else a
+                }
+            }.awaitAll()
+            val cur = _state.value.artists
+            if (cur.map { it.artistId } == artists.map { it.artistId }) {
+                _state.value = _state.value.copy(artists = enriched)
+            }
+        }
+    }
+
     fun loadAlbum(album: ItunesItem) {
         val id = album.collectionId ?: return
         viewModelScope.launch {