chore: update changelog rule

Author: jvsena42

AGENTS.md

@@ -240,7 +240,8 @@ suspend fun getData(): Result<Data> = withContext(Dispatchers.IO) {
 
 ### Changelog
 
-- ALWAYS add an entry under `## [Unreleased]` in `CHANGELOG.md` for `feat:` and `fix:` PRs; skip for `chore:`, `ci:`, `refactor:`, `test:`, `docs:` unless the change is user-facing
+- ALWAYS add exactly ONE entry per PR under `## [Unreleased]` in `CHANGELOG.md` for `feat:` and `fix:` PRs; skip for `chore:`, `ci:`, `refactor:`, `test:`, `docs:` unless the change is user-facing
+- NEVER add multiple changelog lines for the same PR — summarize all changes in a single concise entry
 - USE standard Keep a Changelog categories: `### Added`, `### Changed`, `### Deprecated`, `### Removed`, `### Fixed`, `### Security`
 - ALWAYS append `#PR_NUMBER` at the end of each changelog entry when the PR number is known
 - ALWAYS place new entries at the top of their category section (newest first)