fix: 修复工作流开始表单文案清空回退

- 保留标题和说明的显式空值

- 同步运行页与后端解析逻辑

easyflow-ui-admin/packages/tinyflow-ui/src/utils/workflowNodeFields.test.ts

@@ -855,8 +855,8 @@ describe('workflow node fields', () => {
       systemReserved: true,
     });
     expect(normalized.startFormMeta).toMatchObject({
-      title: '开始问答',
-      description: '请先补充必要信息，再开始执行工作流。',
+      title: '',
+      description: '',
       submitText: '开始',
     });
     expect(normalized.parameters[0]).toMatchObject({

easyflow-ui-admin/packages/tinyflow-ui/src/utils/workflowNodeFields.ts

@@ -439,8 +439,9 @@ function createDefaultStartFormMeta(): StartFormMeta {
 export function normalizeStartFormMeta(meta?: Partial<StartFormMeta> | null): StartFormMeta {
   const fallback = createDefaultStartFormMeta();
   return {
-    title: trimString(meta?.title) || fallback.title,
-    description: trimString(meta?.description) || fallback.description,
+    // Missing values use defaults; an explicit empty string means the user cleared the field.
+    title: meta?.title == null ? fallback.title : trimString(meta.title),
+    description: meta?.description == null ? fallback.description : trimString(meta.description),
     submitText: trimString(meta?.submitText) || fallback.submitText,
   };
 }