fix: respect json structure while truncating tool call strings

[zly2006]

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Link	CommitId	Status	Reason
Detail	f79cbd514095af9c7d3deffd0b8fb501130bf799	🚫 Skipped	No files need to be tested {"packages/global/common/string/tools.ts":"File path does not match include patterns.","packages/service/core/workflow/dispatch/ai/agent/toolCall.ts":"File path does not match include patterns."}

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[c121914yu]

这是啥需求

[zly2006]

这是啥需求

在event: toolCallResponse的返回结果中，data: 后面的内容本来应该是一个合法的json，但是由于这个截断的处理逻辑太武断了，破坏了json结构。本PR的目的在于不破坏json结构的情况下裁剪数据至目标大小。

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[c121914yu]

这是啥需求

在event: toolCallResponse的返回结果中，data: 后面的内容本来应该是一个合法的json，但是由于这个截断的处理逻辑太武断了，破坏了json结构。本PR的目的在于不破坏json结构的情况下裁剪数据至目标大小。

意义是什么？