feat: 完善智能体图片聊天与会话恢复

- 增加私有图片上传、绑定、历史回显与生命周期清理

- 支持输入草稿恢复、图片交互和模型图片能力约束

- 修复旧脏会话幂等删除与前端会话恢复

easyflow-ui-admin/packages/effects/common-ui/src/components/chat-timeline/index.ts

@@ -1,6 +1,7 @@
 export { ChatTimelineBuilder } from './builder';
 export { default as ChatErrorNotice } from './ChatErrorNotice.vue';
 export { default as ChatKnowledgeCard } from './ChatKnowledgeCard.vue';
+export { default as ChatImageAttachments } from './ChatImageAttachments.vue';
 export { default as ChatMessageToolbar } from './ChatMessageToolbar.vue';
 export { default as ChatTextBlock } from './ChatTextBlock.vue';
 export { default as ChatTimeline } from './ChatTimeline.vue';
@@ -11,6 +12,8 @@ export { default as ChatToolCard } from './ChatToolCard.vue';
 export { default as ChatVariantNavigator } from './ChatVariantNavigator.vue';
 export type {
   ChatTimelineErrorItem,
+  ChatImageAttachment,
+  ChatImageLoader,
   ChatTimelineItem,
   ChatTimelineItemStatus,
   ChatTimelineKnowledgeHit,