fix(ui): prevent autoplay when clearing the play queue (#5430)

When clearing the queue, the reducer resets to initialState which lacks
an autoPlay field (undefined). The autoPlay option was computed as true
because undefined !== false, causing the music player library to attempt
playback of the first song before internal state was fully cleared.

Added a queue.length > 0 guard to the autoPlay calculation so it is
never true when the queue is empty, regardless of other state flags.

Fixes #5331

ui/src/audioplayer/Player.jsx

@@ -210,6 +210,7 @@ const Player = () => {
       audioLists: playerState.queue.map((item) => item),
       playIndex: playerState.playIndex,
       autoPlay:
+        playerState.queue.length > 0 &&
         playerState.autoPlay !== false &&
         (playerState.clear || playerState.playIndex === 0),
       clearPriorAudioLists: playerState.clear,