fix(android): keep skip buttons visible in notification

Returning RESULT_ERROR_NOT_SUPPORTED from onPlayerCommandRequest caused
Media3 to mark the skip commands as failed and hide the buttons. Now
returns RESULT_SUCCESS so the notification keeps them enabled, while
ForwardingPlayer no-ops seekToNext/Previous so ExoPlayer never tries to
advance its single-item queue — JS still owns all queue navigation.

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

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

@@ -102,6 +102,8 @@ class MusicService : MediaSessionService() {
         // ExoPlayer drops those commands when its queue has only one item (single-track model),
         // which makes Media3 hide the skip buttons in the notification. JS still owns queue
         // logic — the MediaSession callback intercepts the commands and delegates to JS.
+        // seekToNext* are no-oped here so ExoPlayer never tries to advance its single-item
+        // queue; JS handles all actual navigation via stateListener callbacks.
         val sessionPlayer = object : ForwardingPlayer(player) {
             override fun getAvailableCommands(): Player.Commands =
                 super.getAvailableCommands().buildUpon()
@@ -118,6 +120,11 @@ class MusicService : MediaSessionService() {
                 Player.COMMAND_SEEK_TO_PREVIOUS_MEDIA_ITEM -> true
                 else -> super.isCommandAvailable(command)
             }
+
+            override fun seekToNext()             {}
+            override fun seekToNextMediaItem()    {}
+            override fun seekToPrevious()         {}
+            override fun seekToPreviousMediaItem() {}
         }
 
         // Tapping the notification opens the app directly to the Now Playing screen.
@@ -145,12 +152,14 @@ class MusicService : MediaSessionService() {
                     Player.COMMAND_SEEK_TO_NEXT,
                     Player.COMMAND_SEEK_TO_NEXT_MEDIA_ITEM -> {
                         stateListener?.onSkipToNext()
-                        androidx.media3.session.SessionResult.RESULT_ERROR_NOT_SUPPORTED
+                        // Return SUCCESS so Media3 keeps the button enabled in the notification.
+                        // The ForwardingPlayer no-ops seekToNext so ExoPlayer does nothing.
+                        androidx.media3.session.SessionResult.RESULT_SUCCESS
                     }
                     Player.COMMAND_SEEK_TO_PREVIOUS,
                     Player.COMMAND_SEEK_TO_PREVIOUS_MEDIA_ITEM -> {
                         stateListener?.onSkipToPrevious()
-                        androidx.media3.session.SessionResult.RESULT_ERROR_NOT_SUPPORTED
+                        androidx.media3.session.SessionResult.RESULT_SUCCESS
                     }
                     else -> androidx.media3.session.SessionResult.RESULT_SUCCESS
                 }