build: stable release notes follow the owner's aggregation rules (#328)

A stable body aggregates the changelog since the previous STABLE release,
not since the last beta; in-beta-only bugfixes are excluded by the curator
(the draft lists every candidate with its source section); the small-fixes
filler line is legal only when the range carries user-visible work not
itemised in the body — a single-issue hotfix ships without it, and body
bullets must link their issues so the rule stays checkable.
scripts/release-notes.mjs prints the aggregation draft and verifies
docs/RELEASE-NOTES.md (npm run release:notes -- <tag> [--verify]); the
verifier rejects the v1.68.1-style empty filler by execution. STATUS.md
release mechanics updated in the same commit.

Issue: #328
User-Visible: no

package.json

@@ -32,6 +32,7 @@
     "golden:accept": "node demo/golden/accept.mjs",
     "release:check": "node scripts/release-prerelease.mjs --check",
     "release:prerelease": "node scripts/release-prerelease.mjs",
+    "release:notes": "node scripts/release-notes.mjs",
     "prepare": "node scripts/install-hooks.mjs"
   },
   "devDependencies": {