revert: 还原深浅主题切换

src/styles/global.scss

@@ -529,20 +529,3 @@
     border-radius: 0 4px 4px 0;
   }
 }
-
-// 禁用 view-transition 动画
-::view-transition-old(root),
-::view-transition-new(root) {
-  animation: none;
-  mix-blend-mode: normal;
-}
-
-::view-transition-old(root),
-.dark::view-transition-new(root) {
-  z-index: 1;
-}
-
-::view-transition-new(root),
-.dark::view-transition-old(root) {
-  z-index: 9999;
-}