feat: CMA前端UI优化第三轮P2 — mc-dialog→el-dialog+按钮统一+MapCanvas拆组件+全局过渡动画

frontend/src/style.css

@@ -266,32 +266,6 @@ html.dark .el-dialog__body {
   color: var(--bh-text-regular);
 }
 
-/* 自定义弹窗暗黑适配 */
-html.dark .mc-dialog-overlay,
-html.dark .mc-dialog-overlay-fix {
-  background: rgba(0,0,0,0.7);
-}
-html.dark .mc-dialog-box {
-  background: #1e1e1e;
-  color: #e0e0e0;
-}
-html.dark .mc-dialog-header {
-  border-bottom-color: #333;
-}
-html.dark .mc-dialog-footer {
-  border-top-color: #333;
-}
-html.dark .mc-input {
-  background: #252525;
-  border-color: #333;
-  color: #e0e0e0;
-}
-
-/* 自定义弹窗内下拉选择框层级修复 */
-.dialog-select-popper {
-  z-index: 10001 !important;
-}
-
 /* el-empty 暗黑适配 */
 html.dark .el-empty__description p {
   color: var(--bh-text-secondary);
@@ -404,3 +378,13 @@ html *::after {
               border-color 0.3s ease,
               box-shadow 0.3s ease;
 }
+
+/* 路由过渡动画 — fade */
+.fade-enter-active,
+.fade-leave-active {
+  transition: opacity 0.2s ease;
+}
+.fade-enter-from,
+.fade-leave-to {
+  opacity: 0;
+}