fix(web-admin): zero form-item margin when form-grid is on el-form

Cover label-top dialogs that put form-grid-* class on the form element.

Co-authored-by: Cursor <cursoragent@cursor.com>

web-admin/src/assets/styles/core/app.scss

@@ -1684,6 +1684,10 @@ body {
   margin-bottom: 0;
 }
 
+.el-dialog.dialog-form-layout .el-form--label-top:is(.form-grid, .form-grid-2, .form-grid-3, .form-grid-4, .form-grid-5) > .el-form-item {
+  margin-bottom: 0;
+}
+
 /* 标准 CRUD / 大表单弹窗遮罩：顶对齐留白，避免 align-center 高弹窗与顶栏贴齐（protocol-dialog-mask 同构，全局兜底） */
 .protocol-dialog-mask,
 .lab-test-item-dialog-mask,