docs(changelog): add the 3.18.0 section to the Chinese changelog

[shreemaan-abhishek]

Description

Adds the 3.18.0 section to docs/zh/latest/CHANGELOG.md, the Chinese counterpart of the CHANGELOG.md entry added in #13842, plus its Table of Contents line.

It is a line-for-line translation of the English 3.18.0 section: same three groups (Change / Core / Plugins), same order, same 164 entries, same :warning: markers on the nine backward-incompatible changes. Conventional-commit prefixes, config keys, plugin names and variable names are left in English; only the descriptive text is translated.

Note that the Chinese changelog has not been updated since 3.8.0, so this section sits directly above 3.8.0 and the 3.9.0 to 3.17.0 entries are still missing. Backfilling those is out of scope here.

Local checks: markdownlint, autocorrect --lint ./docs/zh/latest/, utils/fix-zh-doc-segment.py and utils/check-category.py all pass.

Checklist

• I have explained the need for this PR and the problem it solves
• I have explained the changes or the new features added to this PR
• I have added tests corresponding to this change (N/A: documentation only)
• I have updated the documentation to reflect this change
• I have verified that this change is backward compatible (documentation only)