Refactor video playback logic in SlideshowManager for improved fallback handling

Jellyfin.Plugin.MediaBarEnhanced/Web/mediaBarEnhanced.js

@@ -2722,9 +2722,6 @@ const SlideshowManager = {
         endSeconds: player._endTime
       });
       
-      // Explicitly call playVideo to ensure it starts
-      player.playVideo();
-
       if (STATE.slideshow.isMuted) {
         player.mute();
       } else {
@@ -2744,6 +2741,12 @@ const SlideshowManager = {
         }
       }, 1000);
       return true;
+    } else if (player && typeof player.seekTo === 'function') {
+      // Fallback if loadVideoById is not available or videoId missing but player object exists
+      const startTime = player._startTime || 0;
+      player.seekTo(startTime);
+      player.playVideo();
+      return true;
     }
 
     return false;