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/app/src/locales/langs/zh-CN/llm.json

@@ -64,9 +64,9 @@
     "supportTool": "工具",
     "supportAudio": "音频",
     "supportVideo": "视频",
-    "supportImage": "图片",
+    "supportImage": "多模态",
     "supportFree": "免费",
-    "supportImageB64Only": "仅支持Base64图片",
+    "supportImageB64Only": "仅接受 Base64 图片",
     "supportToolMessage": "支持Tool消息"
   },
   "requestPath": "请求路径",