docs: tighten managed mode quickstart title and summary (#8)

# Cookbook contribution

## Summary

- Content type: Recipe（更新已发布内容的元数据）
- Locale: zh-CN
- Demo source included: no
- Target audience: 首次接入 Qoder Cloud Agents API 的开发者
- User problem and expected outcome: 收紧 `managed-mode-quickstart`
的标题（28→31 字）与 summary（约 100→65 字），保留 Managed Mode 以便与未来 Forward Mode
系列对仗，去掉步骤罗列、价值前置，slug 与正文不变。

## Sources and assets

- Public sources used: 无新增
- Asset owner and license: 无外部资产
- All submitted text and assets are original.

## Specialist review

- 不适用，仅元数据文案调整。

## Author checklist

- [x] I used exactly one author and no more than five approved tags.
- [x] The article has at least three `##` sections and no hand-written
table of contents.
- [x] I did not use GitHub Alerts, video, raw HTML, JavaScript, MDX,
iframe, remote images, SVG, or interactive content.
- [x] Images are local PNG, JPEG, or WebP files with meaningful
alternative text and documented rights.（本文无图片）
- [x] The contribution contains no credentials, customer data, personal
information, internal links, or unreleased capabilities.
- [x] If a Demo is included, `demos/<slug>/` matches the owner article,
and the article contains the exact GitHub Demo link.（无 Demo）
- [x] If a Demo is included, its README documents prerequisites, setup,
run, verification, cleanup, and cost/safety considerations.（无 Demo）
- [x] Demo configuration uses placeholders; no dependency cache, build
output, binary, archive, nested Git metadata, or symbolic link is
included.（无 Demo）
- [x] I disclosed the origin and license of Demo source, dependencies,
fixtures, and third-party assets.（无第三方资产）
- [x] I reviewed the generated preview locally or from the required
GitHub Actions checks.
- [x] Every commit contains a `Signed-off-by` trailer.
- [x] I understand that maintainer Merge to `main` is the publication
event.

## Maintainer Demo review

- [x] Not applicable, or a Maintainer reviewed the Demo README and
source manually.
- [x] Not applicable, or the claimed result, cleanup, billable
operations, permissions, and destructive side effects were reviewed.

---------

Signed-off-by: murphy <starhaotian@gmail.com>

Author: starhaotian

content/zh-CN/recipes/managed-mode-quickstart/index.md

@@ -1,8 +1,8 @@
 ---
 schema_version: 1
 slug: managed-mode-quickstart
-title: Managed Mode 快速开始：创建 Session、对话并追踪 Credit 消耗
-summary: 用最小闭环跑通 Qoder Cloud Agents Managed Mode——创建 Session、发送消息、通过 SSE 事件流接收 Agent 回复，并读取每次模型调用的 Credit 消耗与 Session 累计用量。适合首次接入 Cloud Agents API 的开发者。
+title: Managed Mode 快速开始：五个 curl 跑通首次对话
+summary: 五个 curl 命令跑通 Managed Mode 首次对话：创建 Session、发送消息、SSE 接收回复，并看清每一步的 Credit 消耗。
 type: recipe
 category: quick-start
 tags: