fix: 完全隐藏工作流弹窗的默认 header

- 使用 display: none 隐藏 el-dialog__header
- 调整 dialog body 高度为 100vh
- 调整 RuleWorkflow 组件高度为 100vh
- 现在只显示统一的工具栏，不再有重复的 header

frontend/vue-demo/src/components/workflow/RuleWorkflow.vue

@@ -1110,7 +1110,7 @@ defineExpose({
 .rule-workflow {
   display: flex;
   flex-direction: column;
-  height: calc(100vh - 54px);  /* 弹窗高度减去 header */
+  height: 100vh;
   background: #f5f7fa;
 }
 

frontend/vue-demo/src/views/Editor.vue

@@ -7821,14 +7821,12 @@ onMounted(async () => {
 .rule-workflow-dialog {
   :deep(.el-dialog__body) {
     padding: 0;
-    height: calc(100vh - 54px);
+    height: 100vh;
     overflow: hidden;
   }
   
   :deep(.el-dialog__header) {
-    padding: 12px 20px;
-    border-bottom: 1px solid #e4e7ed;
-    margin: 0;
+    display: none;
   }
 }
 </style>