T8513: add .git-blame-ignore-revs to exclude bulk formatting commits (#455)

• T8513: add .git-blame-ignore-revs to exclude bulk formatting commits

• T8513: fix changelog fragment - use trivial section and correct description

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: omnom62 <75066712+omnom62@users.noreply.github.com>