Add Pride feature: implement header color change and cleanup observer for pride effects

Jellyfin.Plugin.Seasonals/Web/pride.js

@@ -55,12 +55,16 @@ function createElements() {
   }
 
   if (colorHeader) {
-      const header = document.querySelector('.skinHeader');
-      if (header) {
-          header.classList.add('pride-header');
-      }
+      document.body.classList.add('pride-active');
   }
 
+  const cleanupObserver = new MutationObserver(() => {
+      if (!document.querySelector('.pride-container')) {
+          document.body.classList.remove('pride-active');
+      }
+  });
+  cleanupObserver.observe(document.body, { childList: true });
+
   const heartEmojis = ['❤️', '🧡', '💛', '💚', '💙', '💜'];
 
   for (let i = 0; i < elementCount; i++) {