feat: 优化工作流字段化参数配置

- 开始节点固定 user_input 并区分系统入口与自定义参数

- LLM 与知识库节点切换为字段值加上游引用配置

- 单节点调试改为字段预览与上游引用输入模式

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

@@ -63,14 +63,20 @@ describe('paramToken utils', () => {
 
     expect(result).toEqual([
       {
+        dataType: undefined,
+        displayName: 'input',
         name: 'input',
         resolved: false,
       },
       {
+        dataType: undefined,
+        displayName: 'docs',
         name: 'docs',
         resolved: true,
       },
       {
+        dataType: undefined,
+        displayName: 'runtimeInput',
         name: 'runtimeInput',
         resolved: true,
       },