update changelog, prepare for 1.5.0

Author: fedorov

CHANGELOG.md

@@ -5,7 +5,7 @@ All notable changes to the IDC Claude Skill are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/),
 and this project adheres to [Semantic Versioning](https://semver.org/).
 
-## [Unreleased]
+## [1.5.0] - 2026-04-08
 
 ### Added