Fix vinyl angle persistence on toggle, group player toggle buttons

- Save vinyl rotation angle before flipping vinylMode flag off
- Wrap vinyl + visualizer buttons in .player-toggles container
- Move margin-left:auto from individual buttons to group

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

media_server/static/js/app.js

@@ -286,6 +286,8 @@
         window.addEventListener('beforeunload', saveVinylAngle);
 
         function toggleVinylMode() {
+            // Save current angle before turning off (must happen while still in vinyl mode)
+            if (vinylMode) saveVinylAngle();
             vinylMode = !vinylMode;
             localStorage.setItem('vinylMode', vinylMode);
             applyVinylMode();