Bilingual changelog · English primary, Chinese translation

Changelog entries are now bilingual pairs: the primary file docs/changelog/<date>-<slug>.md is English, and <date>-<slug>.zh.md is the Chinese translation. The sync script generates the English tree (/changelog/<slug>) from the primary file and the Chinese tree (/zh/changelog/<slug>) from the .zh.md side; RSS, llms sections, and markdown alternates follow each tree’s language.

• Fallback: when one side of a pair is missing, the other language’s entry fills the gap flagged untranslated, and the page plus its feed entry show the notice banner (This page has not been translated yet. / 本页暂未提供中文。) linking to the counterpart.
• Sync / collections: scripts/sync-docs.mjs pairs repo files by base name and writes src/content/changelog/** (the changelog collection) and src/content/changelog-zh/** (the changelog-zh collection); both generated trees stay gitignored.
• Routes: the English routes read changelog, the /zh routes and feeds read changelog-zh; the landing’s recent-changelog block still shows the newest entries, now with English titles.