fix(agent-core): use max output size for compaction budget

[qkunio]

三周前v0.8.0的bug了，现在v0.20.0了，PR还没通过，也没人修，真的希望能解决一下

Related Issue

Resolve #476

Problem

这个版本在v0.8.0的时候就有了，我那时候提了个PR 点击查看，这个只需要1行代码就能解决，但是没人审核，没想到现在还没人通过。

这个问题也很简单的，就是对于OpenAI格式的第三方模型，运行/compact 的时候，只暴露了兜底值reservedContextSize，没有传入模型配置里的 maxOutputSize。只需要传入就好了，我还补了一些测试用例和changeset。感觉是之前写的时候漏掉了这个路径。

What changed

packages/agent-core/src/agent/compaction/full.ts 里添加了一行代码：

maxOutputSize: this.agent.config.maxOutputSize

让上下文压缩的时候，传入的maxOutputSize与普通对话路径 (packages/agent-core/src/agent/index.ts) 保持一致。

同时新增测试用例，验证 compaction 从模型配置读取maxOutputSize作为 hard cap。

before:

after:

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

[changeset-bot]

🦋 Changeset detected

Latest commit: 22844a0

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@moonshot-ai/kimi-code	Patch

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[pkg-pr-new]

pnpm dlx https://pkg.pr.new/@moonshot-ai/kimi-code@22844a0

npx https://pkg.pr.new/@moonshot-ai/kimi-code@22844a0

commit: 22844a0

[wbxl2000]

👍 Thanks for the PR — this will be included in the next release.