feat: 增加智能体对话体验配置

- 支持欢迎语、猜你想问和输入提示的编辑、草稿预览与发布态展示

- 补充配置校验、发布快照持久化和发布后回显修复

easyflow-ui-admin/app/src/components/ai-chat/AiChatPanel.vue

@@ -1,8 +1,8 @@
 <script setup lang="ts">
-import type {AiChatMessage, AiToolApprovalPayload} from './types';
+import type { AiChatMessage, AiToolApprovalPayload } from './types';
 
-import {Close} from '@element-plus/icons-vue';
-import {ElButton} from 'element-plus';
+import { Close } from '@element-plus/icons-vue';
+import { ElButton } from 'element-plus';
 
 import AiConversation from './AiConversation.vue';
 import AiPromptInput from './AiPromptInput.vue';
@@ -13,6 +13,7 @@ defineProps<{
   emptyText?: string;
   loading?: boolean;
   messages: AiChatMessage[];
+  placeholder?: string;
   subtitle?: string;
   title: string;
 }>();
@@ -63,6 +64,7 @@ defineSlots<{
     </slot>
     <AiPromptInput
       :loading="loading"
+      :placeholder="placeholder"
       @send="emit('send', $event)"
       @stop="emit('stop')"
     />