* feat(release): changelog.d/ fragments — kill the CHANGELOG-eat merge-storm cascade
Every PR used to edit the same top lines of CHANGELOG.md (its bullet), so in a
merge-storm each merge conflicted every sibling (CHANGELOG-eat / DIRTY cascade),
forcing a re-sync push + full CI re-run per PR per merge — O(N^2) CI runs.
A PR now adds ONE new file under changelog.d/{features|fixes|maintenance}/ with its
bullet; two PRs never touch the same file. scripts/release/aggregate-changelog.mjs
(npm run changelog:aggregate) folds fragments into the living section and deletes
them at release reconciliation. check:changelog-integrity (already wired in the
merge-integrity CI job — zero workflow change) now also validates fragment
well-formedness. This PR dogfoods the convention: its own entry is a fragment.
* chore(changelog): fragment filename matches PR number (#6783)
Merged into release/v3.8.45. CI merge-integrity fast-gates (changelog-integrity + agent-skills-sync) + pre-flight hermetic mode. O gate novo detectou 11 SKILL.md gerados fora de sync (drift pré-existente no tip: omni-api-keys endpoints, omni-github-skills do #6186) — regenerados neste PR, Merge-integrity GREEN no CI. Reds restantes base-red (dast-smoke/file-size drift/live-data flaky). Testes novos 17/17.
