fix(android): back from album returns to the "all albums" view, not the artist page

The artist screen's "show all albums" overlay state was plain remember(), so
navigating into an album and pressing back reset it — dumping you on the
collapsed artist page instead of the list you came from. Persist which section
is open via rememberSaveable (a String? title) so it survives the round-trip,
and re-derive the overlay entries from the (surviving) categorized albums.

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

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

@@ -26,6 +26,7 @@ import androidx.compose.material.icons.filled.Shuffle
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.material3.*
 import androidx.compose.runtime.*
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.ui.text.input.ImeAction
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -68,11 +69,12 @@ fun ArtistDetailScreen(
     BackHandler(enabled = state.partialAlbum != null) { vm.dismissPartialAlbum() }
     BackHandler(enabled = state.subAlbumItem != null && state.partialAlbum == null) { vm.dismissSubAlbum() }
 
-    var showAllAlbums by remember { mutableStateOf(false) }
+    // Which "all albums" section is expanded (by title), or null. rememberSaveable so it survives
-    var allAlbumsTitle by remember { mutableStateOf("") }
+    // navigating into an album and back — otherwise back would land on the collapsed artist page.
-    var allAlbumEntries by remember { mutableStateOf<List<AllAlbumEntry>>(emptyList()) }
+    var openAllAlbums by rememberSaveable { mutableStateOf<String?>(null) }
+    val showAllAlbums = openAllAlbums != null
     BackHandler(enabled = showAllAlbums && state.partialAlbum == null && state.subAlbumItem == null) {
-        showAllAlbums = false
+        openAllAlbums = null
     }
 
     LaunchedEffect(state.pendingShufflePlay) {
@@ -163,11 +165,35 @@ fun ArtistDetailScreen(
     // Album categories (computed once iTunes data arrives)
     val cats = if (state.iAlbums.isNotEmpty()) categorizeAlbums(artist.album, state.iAlbums) else null
 
+    // Rebuild the overlay entries from the (surviving) categorized albums for whichever section is
+    // open. Derived — not stored — so it's correct after returning from an album.
+    val allAlbumEntries: List<AllAlbumEntry> = when (openAllAlbums) {
+        "In Library" -> cats?.downloaded?.map { (nd, _) ->
+            AllAlbumEntry(name = nd.name, year = nd.year?.toString(), artUrl = coverUrl(nd.coverArt), onClick = { onAlbumClick(nd) })
+        }.orEmpty()
+        "Unvollständig" -> cats?.partial?.map { (nd, ia, counts) ->
+            AllAlbumEntry(
+                name = nd.name, year = nd.year?.toString(),
+                artUrl = ia.artworkUrl100?.replace("100x100bb", "300x300bb") ?: coverUrl(nd.coverArt),
+                badge = "${counts.first}/${counts.second}",
+                onClick = { vm.loadPartialAlbum(nd, ia) }, onDownload = { vm.showDownloadSheet(ia) },
+            )
+        }.orEmpty()
+        "Nicht heruntergeladen" -> cats?.notDownloaded?.map { ia ->
+            AllAlbumEntry(
+                name = ia.collectionName ?: "—", year = ia.releaseDate?.take(4),
+                artUrl = ia.artworkUrl100?.replace("100x100bb", "300x300bb"), dimmed = true,
+                onClick = { vm.loadSubAlbum(ia) }, onDownload = { vm.showDownloadSheet(ia) },
+            )
+        }.orEmpty()
+        else -> emptyList()
+    }
+
     if (showAllAlbums) {
         AllAlbumsOverlay(
-            title   = allAlbumsTitle,
+            title   = openAllAlbums ?: "",
             entries = allAlbumEntries,
-            onBack  = { showAllAlbums = false },
+            onBack  = { openAllAlbums = null },
         )
         return
     }
@@ -349,13 +375,7 @@ fun ArtistDetailScreen(
             if (cats.downloaded.isNotEmpty()) {
                 item {
                     ArtistSectionHeader("In Library", cats.downloaded.size,
-                        onShowAll = if (cats.downloaded.size > 4) ({
+                        onShowAll = if (cats.downloaded.size > 4) ({ openAllAlbums = "In Library" }) else null
-                            allAlbumsTitle = "In Library"
-                            allAlbumEntries = cats.downloaded.map { (nd, _) ->
-                                AllAlbumEntry(name = nd.name, year = nd.year?.toString(), artUrl = coverUrl(nd.coverArt), onClick = { onAlbumClick(nd) })
-                            }
-                            showAllAlbums = true
-                        }) else null
                     )
                 }
                 item {
@@ -379,20 +399,7 @@ fun ArtistDetailScreen(
             if (cats.partial.isNotEmpty()) {
                 item {
                     ArtistSectionHeader("Unvollständig", cats.partial.size,
-                        onShowAll = if (cats.partial.size > 4) ({
+                        onShowAll = if (cats.partial.size > 4) ({ openAllAlbums = "Unvollständig" }) else null
-                            allAlbumsTitle = "Unvollständig"
-                            allAlbumEntries = cats.partial.map { (nd, ia, counts) ->
-                                AllAlbumEntry(
-                                    name  = nd.name,
-                                    year  = nd.year?.toString(),
-                                    artUrl = ia.artworkUrl100?.replace("100x100bb", "300x300bb") ?: coverUrl(nd.coverArt),
-                                    badge = "${counts.first}/${counts.second}",
-                                    onClick = { vm.loadPartialAlbum(nd, ia) },
-                                    onDownload = { vm.showDownloadSheet(ia) },
-                                )
-                            }
-                            showAllAlbums = true
-                        }) else null
                     )
                 }
                 item {
@@ -419,20 +426,7 @@ fun ArtistDetailScreen(
             if (cats.notDownloaded.isNotEmpty()) {
                 item {
                     ArtistSectionHeader("Nicht heruntergeladen", cats.notDownloaded.size,
-                        onShowAll = if (cats.notDownloaded.size > 4) ({
+                        onShowAll = if (cats.notDownloaded.size > 4) ({ openAllAlbums = "Nicht heruntergeladen" }) else null
-                            allAlbumsTitle = "Nicht heruntergeladen"
-                            allAlbumEntries = cats.notDownloaded.map { ia ->
-                                AllAlbumEntry(
-                                    name  = ia.collectionName ?: "—",
-                                    year  = ia.releaseDate?.take(4),
-                                    artUrl = ia.artworkUrl100?.replace("100x100bb", "300x300bb"),
-                                    dimmed = true,
-                                    onClick = { vm.loadSubAlbum(ia) },
-                                    onDownload = { vm.showDownloadSheet(ia) },
-                                )
-                            }
-                            showAllAlbums = true
-                        }) else null
                     )
                 }
                 item {