fix(android): share playlist play conversion + filter unplayable rows

HomeViewModel.playPlaylist (the Home play-button overlay path) and
PlaylistDetailViewModel.play (the detail-screen path) both converted
PlaylistTrackRef -> TrackRef before player.setQueue, but only the
detail-screen path filtered out unplayable rows (missing trackId or
empty streamUrl). Home's path passed them through; Media3 then
silently no-op'd on setUri("") and the queue appeared loaded but
nothing started.

Operator reported "Songs-like playlists queue music that never
plays" via the Home play-overlay 2026-06-01. The same conversion in
two places with different rules is exactly the foot-gun the §1-§3
DRY pass was supposed to head off; this commit adds it as a follow-up
since the playlist-play helper wasn't covered by that sweep.

Extracts `List<PlaylistTrackRef>.toPlayableTrackRefs()` in
playlists/data/PlaylistsRepository.kt. Filters (isAvailable &&
streamUrl non-empty) THEN maps to TrackRef, in one pass. Both call
sites now use it.

The remaining private `toTrackRef()` in PlaylistDetailScreen is kept
for the per-row TrackActionsButton wiring - the actions menu only
needs id+display fields and doesn't queue anything itself.

android/app/src/main/java/com/fabledsword/minstrel/home/ui/HomeScreen.kt

@@ -69,6 +69,7 @@ import com.fabledsword.minstrel.nav.ArtistDetail
 import com.fabledsword.minstrel.nav.Home
 import com.fabledsword.minstrel.nav.PlaylistDetail
 import com.fabledsword.minstrel.playlists.data.PlaylistsRepository
+import com.fabledsword.minstrel.playlists.data.toPlayableTrackRefs
 import com.fabledsword.minstrel.playlists.widgets.OfflinePoolCard
 import com.fabledsword.minstrel.playlists.widgets.PlaylistCard
 import com.fabledsword.minstrel.playlists.widgets.PlaylistPlaceholderCard
@@ -274,20 +275,10 @@ class HomeViewModel @Inject constructor(
                 )
                 return@launch
             }
-            val tracks = detail.tracks.mapNotNull { row ->
-                row.trackId?.let { trackId ->
-                    TrackRef(
-                        id = trackId,
-                        title = row.title,
-                        albumId = row.albumId.orEmpty(),
-                        albumTitle = row.albumTitle,
-                        artistId = row.artistId.orEmpty(),
-                        artistName = row.artistName,
-                        durationSec = row.durationSec,
-                        streamUrl = row.streamUrl.orEmpty(),
-                    )
-                }
-            }
+            // Shared with PlaylistDetailViewModel.play - filters out
+            // unplayable rows (missing trackId or empty streamUrl) so the
+            // queue can't end up with tracks Media3 silently rejects.
+            val tracks = detail.tracks.toPlayableTrackRefs()
             if (tracks.isEmpty()) {
                 poolMessages.trySend("Mix isn't ready yet - try again in a moment")
                 return@launch

android/app/src/main/java/com/fabledsword/minstrel/playlists/data/PlaylistsRepository.kt

@@ -12,6 +12,7 @@ import com.fabledsword.minstrel.cache.db.entities.CachedPlaylistTrackEntity
 import com.fabledsword.minstrel.cache.mutations.MutationQueue
 import com.fabledsword.minstrel.models.PlaylistRef
 import com.fabledsword.minstrel.models.PlaylistTrackRef
+import com.fabledsword.minstrel.models.TrackRef
 import com.fabledsword.minstrel.models.wire.PlaylistDetailWire
 import com.fabledsword.minstrel.models.wire.PlaylistTrackWire
 import com.fabledsword.minstrel.models.wire.PlaylistWire
@@ -204,6 +205,31 @@ data class PlaylistDetailRef(
     val tracks: List<PlaylistTrackRef>,
 )
 
+/**
+ * Convert each [PlaylistTrackRef] to a player-ready [TrackRef], dropping
+ * any row that isn't actually playable (trackId missing OR streamUrl
+ * missing). The two call sites (PlaylistDetailViewModel.play and
+ * HomeViewModel.playPlaylist) used to hand-roll this conversion and
+ * differed on whether they applied the filter, which let unplayable
+ * tracks reach `player.setQueue` and silently no-op inside Media3
+ * (setUri("") never errors). Centralise both the conversion AND the
+ * defensive filter so the queue is always playable.
+ */
+fun List<PlaylistTrackRef>.toPlayableTrackRefs(): List<TrackRef> =
+    filter { it.isAvailable && !it.streamUrl.isNullOrEmpty() }
+        .map { row ->
+            TrackRef(
+                id = row.trackId.orEmpty(),
+                title = row.title,
+                albumId = row.albumId.orEmpty(),
+                artistId = row.artistId.orEmpty(),
+                albumTitle = row.albumTitle,
+                artistName = row.artistName,
+                durationSec = row.durationSec,
+                streamUrl = row.streamUrl.orEmpty(),
+            )
+        }
+
 // ── Mappers (internal — keep Room + wire types out of the UI layer) ──
 
 private fun CachedPlaylistEntity.toDomain(): PlaylistRef =

android/app/src/main/java/com/fabledsword/minstrel/playlists/ui/PlaylistDetailScreen.kt

@@ -69,6 +69,7 @@ import com.fabledsword.minstrel.player.PlayerController
 import com.fabledsword.minstrel.likes.data.LikesRepository
 import com.fabledsword.minstrel.playlists.data.PlaylistDetailRef
 import com.fabledsword.minstrel.playlists.data.PlaylistsRepository
+import com.fabledsword.minstrel.playlists.data.toPlayableTrackRefs
 import com.fabledsword.minstrel.shared.formatDuration
 import com.fabledsword.minstrel.shared.widgets.TrackRow
 import com.fabledsword.minstrel.shared.widgets.LikeButton
@@ -223,9 +224,8 @@ class PlaylistDetailViewModel @Inject constructor(
 
     /** Play the available tracks starting at [startTrackId] (or first available). */
     fun play(tracks: List<PlaylistTrackRef>, startTrackId: String?) {
-        val playable = tracks.filter { it.isAvailable && !it.streamUrl.isNullOrEmpty() }
-        if (playable.isEmpty()) return
-        val refs = playable.map { it.toTrackRef() }
+        val refs = tracks.toPlayableTrackRefs()
+        if (refs.isEmpty()) return
         val startIndex = refs.indexOfFirst { it.id == startTrackId }.coerceAtLeast(0)
         player.setQueue(refs, initialIndex = startIndex, source = "playlist:$playlistId")
     }