Fix fumadocs-mdx validation: flatten nested pages in concepts meta.json

[Copilot]

CI build failing on meta.json validation - fumadocs-mdx expects flat string arrays in pages, not nested objects.

Changes

• Flattened pages array in /content/docs/concepts/meta.json and meta.cn.json
• Removed nested "Protocol Namespaces" grouping object at pages[3]
• All protocol-* entries now at top level

Before:

{
  "pages": [
    "manifesto",
    "architecture",
    {
      "title": "Protocol Namespaces",
      "pages": ["protocol-data", "protocol-driver", ...]
    },
    "terminology"
  ]
}

After:

{
  "pages": [
    "manifesto",
    "architecture",
    "protocol-data",
    "protocol-driver",
    ...,
    "terminology"
  ]
}

Sidebar navigation will show protocol pages in sequence rather than nested under a group heading.

Original prompt

引用: https://github.com/objectstack-ai/spec/actions/runs/21345690146/job/61432691384#step:8:1

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Project	Deployment	Review	Updated (UTC)
spec	Error		Jan 26, 2026 4:00am

[Copilot]

Pull request overview

This PR fixes a CI build failure by updating the fumadocs-mdx metadata structure in the concepts documentation. The nested "Protocol Namespaces" grouping structure was causing validation errors because fumadocs-mdx expects flat string arrays in the pages field, not nested objects.

Changes:

• Flattened the pages array structure in both English and Chinese concept meta files
• Removed the nested "Protocol Namespaces" grouping object
• Maintained all 11 protocol pages at the top level in the same sequential order

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
content/docs/concepts/meta.json	Flattened pages array from nested structure to flat list of protocol page references
content/docs/concepts/meta.cn.json	Flattened pages array from nested structure to flat list (Chinese version)