[Bug]: CoPaw主进程陷入工具调用错误重试循环，导致CPU持续126.7%

## CoPaw Version

[Provide the version of CoPaw you are using, e.g. 0.x.x or git commit hash.]
[Using `copaw --version` in your command line or checking the version in the console UI can help.]
CoPaw主进程陷入工具调用错误重试循环，导致CPU持续126.7%、线程爆炸（101个）、上下文切换飙高（170k+/秒）。
## Description

[Describe the bug clearly and concisely. What happened vs what you expected?]

**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

- **CoPaw version:** [e.g. 0.x.x or git commit]
- **OS:** [e.g. macOS 14, Ubuntu 22.04, Windows 11]
- **Install method:** [pip / one-line install / Docker / from source]
- **Python version (if applicable):** [e.g. 3.10]

## Steps to Reproduce

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## Actual vs Expected

- **Actual:**
- **Expected:**

## Logs / Screenshots

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

```
(paste logs here)
```

## Additional Notes

[Optional: workarounds, similar issues, etc.]