fix: stop ExoPlayer shuffle conflict causing end-of-queue desync

When reaching the last shuffled song, the UI changed but audio kept playing
the same song. Root cause: ExoPlayer still had its own shuffle mode on (set
in onReady), so its auto-advance and _nsBridge('next') picked random indices
that conflicted with the pre-shuffled JS array.

- setShuffleMode always false: we own the playback order via pre-shuffled
  JS array, ExoPlayer must advance sequentially through it
- Remove _nsBridge('next') fallback: never let ExoPlayer decide the next
  song autonomously. End of queue with no repeat = let ExoPlayer stop.

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

src/player.js

@@ -130,8 +130,10 @@ window.NSPlayer = {
       } catch (e) {}
     }
     // Always sync shuffle/repeat settings.
+    // setShuffleMode is always false — we pre-shuffle the JS array ourselves and
+    // traverse sequentially, so ExoPlayer's internal shuffle must stay off.
     _nsBridge('setRepeatMode',  S.repeat  === false ? 'off' : S.repeat);
-    _nsBridge('setShuffleMode', S.shuffle);
+    _nsBridge('setShuffleMode', false);
   },
 
   // Play/pause/buffer state changed.
@@ -714,10 +716,7 @@ export function nextSong() {
       // Explicit index prevents desync when JS and native queue pointers diverge.
       _nsBridge('seekToIndex', ni, 0);
       _nsBridge('play');
-    } else {
+    // else: ni = -1 means end of queue with no repeat — let ExoPlayer stop naturally.
-      // Shuffle mode: native picks the shuffled-next item; onTrackChanged will confirm the index.
-      _nsBridge('next');
-    }
     if (S.radioMode && S.queue.length - S.qIdx < 5) fillRadioQueue();
     return;
   }