update changelog with v0.2.0 release date

Author: simi

CHANGELOG.md

@@ -5,7 +5,7 @@ All notable changes to Ruby Butler will be documented in this file.
 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]
+## [0.2.0] - 2025-10-19
 
 ### Added
 - Configuration file support via `rb.toml` or `rb.kdl` for global settings