PR #457 R6 polish: harmonize PR-B CHANGELOG bullet with R-parity close-out

R6 verdict was Looks good with 1 P3 informational item: the older PR-B
audit bullet at CHANGELOG.md:13 (added in PR #454) still described
the pre-goldens deferral state ("JSON goldens deferred", "TestBaconParityR
skips with a pointer when goldens missing", "status flipped to
**Complete (R parity goldens pending)**"). That contradicts the new
PR-457 bullet at CHANGELOG.md:11 (committed goldens + 4 active parity
tests) within the same [Unreleased] section, so the release notes
read as internally inconsistent.

Updated 3 strings in the PR-B bullet to reflect the within-release
close-out:
- Status flip wording: now says the (R parity pending) caveat was
  closed by the parity-goldens bullet above in this same release.
- TestBaconParityR description: 4 tests, all active post-release;
  skips only in partial-checkout scenarios.
- (4) outcome: parity goldens deferral was closed within this release.

Author: igerber