[Bug]: 错误的创建新会话

## QwenPaw Version

主干：截止到a403b2433af6ac74404d69fc80a289658996226e提交

## Description

1、点击新建任务，创建一个新会话，然后随便问一句，等待AI回答完成，此时历史会话里会多一个新增的会话
2、再次点击新建任务，然后点击上一步自动创建出来的会话，并且在这个会话里进行第二次提问
3、会发现侧边栏又创建了一个会话，而不是延续在刚才的会话里

**Related PR(s):** #(optional)

**Security considerations:** [If applicable, e.g. auth, env/config exposure]

## Component(s) Affected

- [√] Core / Backend (app, agents, config, providers, utils, local_models)
- [√] Console (frontend web UI)
- [ ] Channels (DingTalk, Feishu, QQ, Discord, iMessage, etc.)
- [ ] Skills
- [ ] CLI
- [ ] Documentation (website)
- [ ] Tests
- [ ] CI/CD
- [ ] Scripts / Deploy

## Environment

- **QwenPaw version:** [a403b2433af6ac74404d69fc80a289658996226e git commit]
- **OS:** [ Windows 10 ]
- **Install method:** [桌面APP安装]
- **Python version (if applicable):** [e.g. 3.10]

## Steps to Reproduce
如上所示
## Actual vs Expected

- **Actual:** 创建新会话
- **Expected:** 延续点击的会话

## Logs / Screenshots

[Paste relevant log output or attach screenshots. Use code blocks for logs.]

```
(paste logs here)
```

## Additional Notes

[Optional: workarounds, similar issues, etc.]