chore(changelog): move the unless entry to the version that ships it

[haribo]

Summary

The unless removal (#619) was documented under ## [0.12.0] — a version tagged and published before that work existed. The changelog therefore claimed a fix shipped in a release that does not contain it.

My mistake, and a mechanical one: the script that inserted the entry replaced the first ### Changed in the file, which belonged to the released section because [Unreleased] had none yet.

A second consequence, worth naming

test/changelog-rule.sh only checks [Unreleased], so the entry was never measured against the word ceiling. Moved into place it came out at 62 words, over the 60 limit — it has been shortened, which is the only wording change here.

Why a separate PR rather than folding this into the release roll

The correction concerns v0.12.0, already published; the roll concerns the version being prepared. And /release says in as many words not to edit entries during the roll — so the fix lands before it, not inside it.

Test plan

• The entry no longer appears in the [0.12.0] section, and appears once under [Unreleased] / Changed.
• test/changelog-rule.sh green — which is now meaningful for this entry for the first time.
• No other entry moved: the seven Fixed lines added since the release were already in the right place, checked one by one.