Generate changelog entries for changes on the current branch relative to main, then sync to the docs site.

Steps

Inspect: git log main..HEAD --oneline + git diff main..HEAD --stat.
Edit root CHANGELOG: add bullets under ## Unreleased in CHANGELOG.md using the prefix table below. For changes scoped to a subpackage under packages/ or sdks/, also update that subpackage's CHANGELOG.md — subpackage CHANGELOGs follow their own prefix conventions (e.g. packages/kosong/CHANGELOG.md uses provider prefixes like Kimi: / Anthropic:); only the root CHANGELOG follows the table below.
Sync English docs: node docs/scripts/sync-changelog.mjs.
Translate to Chinese: hand-write equivalents under ## 未发布 in docs/zh/release-notes/changelog.md. Use the full-width colon ：. Follow docs/AGENTS.md terminology.
Breaking changes: if any, add a section under ## Unreleased in docs/en/release-notes/breaking-changes.md with Affected + Migration subsections, and under ## 未发布 in docs/zh/release-notes/breaking-changes.md with 受影响 + 迁移 subsections.

Entry format

- <Prefix>: <verb-led sentence, readable standalone> — <optional rationale / before-after / migration>