fix(web-admin): tighten label-top row spacing for all dialog grids

Zero form-item margin inside .form-grid* and add dialog fallback spacing.

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

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

@@ -1490,6 +1490,18 @@ body {
   gap: 12px 12px;
 }
 
+/* 纵向间距交给 gap，避免与 el-form-item 默认 margin-bottom 叠加 */
+.form-grid,
+.form-grid-2,
+.form-grid-3,
+.form-grid-4,
+.form-grid-5 {
+  > .el-form-item,
+  > .el-form-item.el-form-item--label-top {
+    margin-bottom: 0;
+  }
+}
+
 .form-col-span-2 {
   grid-column: 1 / -1;
 }
@@ -1658,6 +1670,20 @@ body {
   flex-shrink: 0;
 }
 
+/* label-top 弹窗：无栅格时也收紧默认 18px 行距 */
+.el-dialog.dialog-form-layout .el-form--label-top > .el-form-item,
+.el-dialog.dialog-form-layout .el-form--label-top > .el-row .el-form-item {
+  margin-bottom: 12px;
+}
+
+.el-dialog.dialog-form-layout .el-form--label-top .form-grid .el-form-item,
+.el-dialog.dialog-form-layout .el-form--label-top .form-grid-2 .el-form-item,
+.el-dialog.dialog-form-layout .el-form--label-top .form-grid-3 .el-form-item,
+.el-dialog.dialog-form-layout .el-form--label-top .form-grid-4 .el-form-item,
+.el-dialog.dialog-form-layout .el-form--label-top .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,