[Bug] 插件 tool-call 参数含全角中文标点时报 UnicodeEncodeError (lone surrogate)

**提交人**: 老宏
**客户端版本**: 0.1.38

---

**现象**
Windows 10 上，调用一个带 node worker 的 chip 插件（`node` slot，`json-rpc-stdio` 协议），tool-call 参数里含全角中文标点（如 `：`、`。`、`，`）时，host 报错：

```
UnicodeEncodeError: 'utf-8' codec can't encode character '\udcb7' in position 206: surrogates not allowed
```

**复现步骤**
1. 任意 chip 插件，`slots: ["tool","node"]`，node entry 为 `node/worker.cjs`，protocol `json-rpc-stdio`
2. main.js 收到 tool-call 后转发给 node worker
3. 参数含全角中文标点（例如 `text: "测试：中文冒号"`，仅 7 个字符）
4. host 报 `UnicodeEncodeError ... surrogates not allowed`

**补充观察**
- 纯汉字（无标点）的长参数正常；一旦含全角标点（UTF-8 3 字节 CJK 符号区间）立即触发
- 与参数长度无关（7 字符即复现）
- 错误发生在 host 序列化阶段：插件侧（main.js / worker / Python bridge）各自做 surrogate 清理只能缓解，无法根治，因为到达插件层时字符串已被拆成 lone surrogate
- 不经 node worker 的其它插件用同样中文参数正常 → 疑似与 node worker 转发链路的参数编码有关

**期望行为**
含全角中文标点的参数正常编码传递到插件，不产生 lone surrogate。
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**版本区域**: CN
**OS**: win32 x64 (10.0.19045)
**界面语言**: zh-CN

Start by reproducing the Windows win32 failure through the host serialization path with a node/worker.cjs entry using the json-rpc-stdio protocol. Trace the value through main.js and the Python bridge to identify where the lone surrogate appears. Done means full-width Chinese punctuation reaches the node worker intact without UnicodeEncodeError.

Written by the indexing model from the issue text.