docs: restore Kimi Datasource legacy pages

[wbxl2000]

Related Issue

No linked issue. The deployed documentation URL /zh/customization/datasource.html returns 404 after Kimi Datasource was merged into the Plugins page.

Problem

PR #551 removed the standalone datasource pages and added redirect-style config that VitePress/GitHub Pages does not use for static deployment. As a result, GitHub Pages has no datasource.html file to serve for existing bookmarks and search results.

What changed

• Restore lightweight English and Chinese customization/datasource.md pages so VitePress generates the legacy .html URLs again.
• Add a meta refresh and visible link from each legacy page to the Kimi Datasource section on the Plugins page.
• Remove the unsupported redirects config and the dev-only redirect middleware so local behavior does not hide deployment behavior.

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. (N/A: docs-only; verified with docs build.)
• Ran gen-changesets skill, or this PR needs no changeset. (No changeset needed: docs-only.)
• Ran gen-docs skill, or this PR needs no doc update. (N/A: this PR directly updates docs.)

Verification

• git diff --check
• pnpm -C docs run build
• env VITEPRESS_BASE=/kimi-code/ pnpm -C docs run build

[pkg-pr-new]

pnpm dlx https://pkg.pr.new/@moonshot-ai/kimi-code@666c735

npx https://pkg.pr.new/@moonshot-ai/kimi-code@666c735

commit: 666c735

[changeset-bot]

⚠️ No Changeset found

Latest commit: 666c735

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