fix: suppress spurious onQueueEnded after reconnect; handle STATE_ENDED on reopen; add isEnded to snapshot

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

android/app/src/main/kotlin/com/novasonic/app/MainActivity.kt

@@ -249,6 +249,7 @@ class MainActivity : AppCompatActivity(), MusicService.StateListener {
         val json = JSONObject().apply {
             put("isPlaying",    ctrl.isPlaying)
             put("isBuffering",  ctrl.playbackState == Player.STATE_BUFFERING)
+            put("isEnded",      ctrl.playbackState == Player.STATE_ENDED)
             put("currentIndex", ctrl.currentMediaItemIndex)
             put("currentId",    ctrl.currentMediaItem?.mediaId ?: "")
             put("positionMs",   ctrl.currentPosition)