docs: add changelog entry for systray fixes (#4910)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: leaanthony

v3/UNRELEASED_CHANGELOG.md

@@ -23,6 +23,8 @@ After processing, the content will be moved to the main changelog and this file
 
 ## Fixed
 <!-- Bug fixes -->
+- Fix system tray menu highlight state on macOS - icon now shows selected state when menu is open (#4910)
+- Fix system tray attached window appearing behind other windows on macOS - now uses proper popup window level (#4910)
 
 ## Deprecated
 <!-- Soon-to-be removed features -->