feat: 完成工作流开始节点开场表单

- 增加开始节点 startFormMeta/startFormSchema 配置与运行参数解析

- 统一 Admin/UserCenter 开场表单渲染与文件集合输入

- 补充开始表单校验、引用迁移和前端工具测试

easyflow-ui-admin/app/src/views/ai/workflow/WorkflowDesign.vue

@@ -376,7 +376,7 @@ async function getWorkflowInfo(workflowId: any) {
       : {};
     tinyFlowData.value = isWorkflowDataEmpty(parsedContent)
       ? createInitialWorkflowData()
-      : parsedContent;
+      : normalizeWorkflowStartNodes(parsedContent);
     syncNavTitle(workflowInfo.value?.title || '');
   });
 }