docs: fix router auto language redirect

[RealKai42]

Summary

• Fix landing page auto-redirect by calling useRouter() in setup (not inside onMounted) and wrapping paths with withBase() so it works on GitHub Pages subpaths.

Test plan

• Visit docs root with navigator.language starting with zh → auto-redirects to /zh/
• Visit docs root with English browser → auto-redirects to /en/
• Manual hero buttons still work under base path

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[chatgpt-codex-connector]

💡 Codex Review

kimi-cli/docs/index.md

Lines 23 to 26 in 3a5f957

	if (lang.startsWith('en')) {
	router.go(withBase('/en/'))
	} else {
	router.go(withBase('/zh/'))

Keep English as the fallback locale

For browsers whose navigator.language is neither Chinese nor English (for example fr-FR, ja-JP, or an empty value), this condition now falls through to /zh/. Before this commit, all non-zh browsers landed on English, and the README's primary documentation links also point at /en/, so this regresses the default experience for most non-Chinese users. Check zh explicitly and keep /en/ as the fallback.

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