Enhance CSS animations and performance across seasonal styles; add will-change property for smoother transitions and optimize keyframes. [skip ci]

Jellyfin.Plugin.Seasonals/Web/eid.css

@@ -9,6 +9,7 @@
     z-index: 10;
     contain: strict;
     overflow: hidden;
+    contain: layout paint;
 }
 
 .eid-symbol {
@@ -18,12 +19,14 @@
 }
 
 .eid-symbol.floating-star {
+    will-change: opacity;
     opacity: 0;
     animation: eid-twinkle 4s ease-in-out infinite;
     mix-blend-mode: screen;
 }
 
 .lantern-rope {
+    will-change: transform;
     position: absolute;
     top: 0;
     width: 2px;