feat(web+android): search play queues only the tapped song (radio fills the rest)

Playing a song from search results queued the whole result list. Now it plays only
the clicked song; Radio mode, if on, fills the rest — closer to Spotify. Both
platforms already trigger a radio top-up on the first track (web playQueue →
fillRadioQueue; Android onMediaItemTransition → checkRadioRefill), so no extra wiring
is needed. Album/playlist play still queues the full list. Bump SW cache to ns-v44.

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

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

@@ -343,7 +343,8 @@ private fun LibrarySearchContent(
                     coverUrl = coverUrl(song.coverArt),
                     isPlaying = playerState.currentSong?.id == song.id,
                     starred  = song.starred != null,
-                    onPlay   = { onSongPlay(songs, idx) },
+                    // Play only the tapped song; Radio mode (if on) fills the rest.
+                    onPlay   = { onSongPlay(listOf(song), 0) },
                     onMore   = onShowContextMenu?.let { cb -> { cb(song) } },
                 )
             }

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

@@ -57,12 +57,12 @@ fun SearchScreen(
                     if (r.song.isNotEmpty()) {
                         item { ResultHeader("Songs") }
                         items(r.song, key = { it.id }) { song ->
-                            val idx = r.song.indexOf(song)
                             SongRow(
                                 song = song,
                                 coverUrl = coverUrl(song.coverArt),
                                 isPlaying = playerState.currentSong?.id == song.id,
-                                onPlay = { onSongPlay(r.song, idx) },
+                                // Play only the tapped song; Radio mode (if on) fills the rest.
+                                onPlay = { onSongPlay(listOf(song), 0) },
                             )
                         }
                     }