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/builder.ts

@@ -319,7 +319,7 @@ export const ChatTimelineBuilder = {
     metadata?: Partial<ChatTimelineMessageItem>,
   ) {
     const text = normalizeText(content);
-    if (!text) {
+    if (!text && !metadata?.images?.length) {
       return;
     }
     const item: ChatTimelineMessageItem = {
@@ -327,13 +327,15 @@ export const ChatTimelineBuilder = {
       role: 'user',
       status: 'done',
       createdAt: Date.now(),
-      parts: [
-        {
-          id: createId('text'),
-          content: text,
-          type: 'text',
-        },
-      ],
+      parts: text
+        ? [
+            {
+              id: createId('text'),
+              content: text,
+              type: 'text' as const,
+            },
+          ]
+        : [],
       type: 'message',
       ...metadata,
     };