style(frontend): C-3 补漏·custom-tab-bar dim-fan-circle/label transition:all 显式化

fan-active 均改 opacity+transform -> 按属性过渡（弹性缓动保留）
审计脚本 transition:all 指标归零

cfc-frontend/custom-tab-bar/index.vue

@@ -285,7 +285,7 @@ export default {
   justify-content: center;
   opacity: 0;
   transform: scale(0);
-  transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
+  transition: opacity 0.3s cubic-bezier(0.34, 1.56, 0.64, 1), transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
   box-shadow: 0 4rpx 16rpx rgba(0,0,0,0.15);
 }
 .dim-fan-circle.fan-active {
@@ -304,7 +304,7 @@ export default {
   text-align: center;
   opacity: 0;
   transform: translateY(-10rpx);
-  transition: all 0.3s ease;
+  transition: opacity 0.3s ease, transform 0.3s ease;
 }
 .dim-fan-label.fan-active {
   opacity: 1;