style(layout): 优化导航栏右侧菜单项样式

- 移除菜单项的底部边距
- 为非最后一个菜单项添加底部边距，保持间距一致性

src/layouts/components/navbar/components/right-side/index.vue

@@ -231,7 +231,6 @@ const handleSubAccountClick = (item) => {
 
     .ant-dropdown-menu-item {
       padding: 0 12px;
-      margin-bottom: 8px;
       font-family: $font-family-regular;
       color: var(--Text-1, #211f24);
       font-size: 14px;
@@ -239,6 +238,10 @@ const handleSubAccountClick = (item) => {
       font-weight: 400;
       line-height: 22px;
 
+      &:not(:last-child) {
+        margin-bottom: 8px;
+      }
+
       .ant-dropdown-menu-title-content {
         display: flex;
         height: 32px;