fix(ci): aggregated release notes across silent intervening tags

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

package.json

@@ -104,7 +104,7 @@
     "build:native": "bun --cwd=packages/natives run build",
     "test": "bun run --parallel test:ts test:rs",
     "test:ts": "GITHUB_ACTIONS= bun run --workspaces --if-present test -- --only-failures && bun run test:scripts",
-    "test:scripts": "bun test scripts/ci-concurrency.test.ts",
+    "test:scripts": "bun test scripts/ci-concurrency.test.ts scripts/ci-release-notes.test.ts",
     "test:rs": "bun scripts/run-rs-task.ts test:rs",
     "check": "bun run --parallel check:ts check:rs",
     "check:ts": "bun run check:tools && bun run --workspaces --if-present check",