📝(changelog) reorganize sections to match Keep a Changelog convention

Reorder CHANGELOG section headings to follow standard Keep a Changelog format
(Added, Changed, Deprecated, Removed, Fixed, Security) for consistent structure
that users expect when reviewing release notes.

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0),
 and this project adheres to
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
 ## [1.0.1] - 2025-12-17
 
 ### Changed
@@ -16,5 +18,3 @@ and this project adheres to
 - ♿(frontend) indicate external link opens in new window on feedback #816 
 - ♿(frontend) fix heading level in modal to maintain semantic hierarchy #815
 - ♿️(frontend) Improve focus management when opening and closing chat #807
-
-## [Unreleased]