scripts/ci-release-notes.ts previously extracted only the single
target-version section, so changelog entries finalized under tags pushed
without a GitHub Release (e.g. v15.12.5 and v15.12.6 — collateral from
the pre-#2564 release-cancellation bug) were stranded out of the next
published release body.
The generator now walks the range (latest-published-release, target],
resolved via 'gh release list', and merges every in-range '## [X.Y.Z]'
section per package — grouped by '### <category>' with bullet-level
dedup so post-release changelog flattening cannot surface the same
entry twice. Versions iterate newest-first so newer phrasing wins on
dup resolution, and categories are sorted into the canonical
Breaking/Added/Changed/Fixed/Removed order regardless of source order.
Falls back to legacy single-version extraction when 'gh' is unavailable
or no prior published release resolves (safe no-op);
'OMP_RELEASE_NOTES_FLOOR=v15.12.4' overrides the lookup for manual
re-runs (empty string forces legacy mode).
Adds scripts/ci-release-notes.test.ts covering: range inclusion above
floor, target-inclusive boundary, dedup of bullets flattened forward
into multiple versions, canonical category ordering, the null-floor
legacy fallback, empty version sections skipped, and no empty-category
emission when dedup drains a bucket. Wired into 'bun run test:scripts'.
Fixes#2596
roboomp