Update CHANGELOG with powerMonitor fix

Agent-Logs-Url: https://github.com/hovancik/stretchly/sessions/35717b1c-36ce-4588-9c12-30d216ec10f2

Co-authored-by: hovancik <4745859+hovancik@users.noreply.github.com>

Author: Copilot

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+### Fixed
+- fix duplicate powerMonitor listeners accumulating on system resume or screen unlock
 
 ## [1.21.0] - 2026-04-25
 ### Added