docs: add changelog-accuracy lesson and pre-tag eval

CLAUDE.md

@@ -356,6 +356,7 @@ Keep rules general, evidence-backed, and under 20 words. Never add secrets, pers
 - Never `fetch` a provider from content/popup — route through the background worker.
 - Bump `version` in `package.json` only (+ lockfile); the manifest derives it via `pkg.version`.
 - Style inline; Tailwind classes do nothing until PostCSS is wired.
+- Verify CHANGELOG entries against code, not commit subjects or handoff summaries.
 
 ## Memory protocol