docs: Fix AstronClaw links and improve Loomy quick-start documentation

[bbdu3]

Description

Improved the AstronClaw and Loomy markdown and json:

1. Fix the AstronClaw deployment link

The deployment link in docs/en/guide/astronclaw/introduction.md (line 9) pointed to OpenClaw instead of AstronClaw. Updated to use the correct link.

2. Improve Weibo channel information consistency in document

The description of supported message channels in the last section of docs/guide/astronclaw/introduction.md and docs/en/guide/astronclaw/introduction.md was inconsistent between Chinese and En versions.

Since Weibo is already supported in the project, the Weibo channel information has been added and synchronized across the related documentation:

• docs/guide/astronclaw/introduction.md
• docs/guide/astronclaw/getting-started.md
• docs/en/guide/astronclaw/getting-started.md

3. Improve the Loomy quick-start flow

Add a Download and install Loomy title in the quick-start.md :

Chinese version:

## 下载并安装 Loomy

English version:

## Download and Install Loomy

This improves the quick-start.md structure and makes the markdown structure clearer and more consistent.

Validation

• Executed npm run docs:build; VitePress completed the build successfully without any build or page rendering errors.
• Confirmed that the JSON content can be parsed correctly.
• Confirmed that the Markdown files are processed correctly by VitePress.

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All committers have signed the CLA.