docs: fix broken API reference links in zh/ja/ko translations

[Tym216]

Summary

Fix 27 broken relative links in the translated docs (docs/zh, docs/ja, docs/ko).

The API reference pages live under docs/ref/ (English only). From a page under docs/{zh,ja,ko}/, the current ref/... links resolve to a non-existent docs/{zh,ja,ko}/ref/ path, which 404s on the published site (for example, docs/zh/testing.md → ref/testing.md resolves to /zh/ref/testing.md).

This PR adds the missing ../ prefix so the links resolve to the shared English reference pages (../ref/...).

Test plan

• Verified all 9 link targets exist under docs/ref/ (e.g. ref/testing.md, ref/mcp/manager.md, ref/extensions/experimental/codex/*.md)
• Confirmed no remaining ](ref/ links under docs/zh, docs/ja, docs/ko
• English docs are unchanged
• Docs-only change (no code changes)

Issue number

N/A

Checks

• I've added new tests, if relevant
• I've run .agents/skills/code-change-verification/scripts/run.sh (skipped: docs-only change)
• I've confirmed all verification steps pass
• If using Codex, I've run /review before submitting this PR

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Make the link correction in the translation generator

When any corresponding English page is retranslated, translate_docs.py recreates this generated file from the English source, whose URL remains ref/lifecycle.md, and the translation prompt explicitly preserves link URLs; this will therefore overwrite the added prefix and reintroduce the broken link. Implement the relative-link adjustment in the translation pipeline and regenerate the localized pages rather than editing generated translations directly.

AGENTS.md reference: AGENTS.md:L178-L179

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[seratch]

This could only happen with preview on github.com; the live document site doesn't have the issue at all.