docs: mark CHANGELOG as v1.0.0 release

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: TheSmallPixel

CHANGELOG.md

@@ -5,7 +5,7 @@ All notable changes to this project are documented here.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [1.0.0] - 2026-05-05
 
 ### Added
 - MIT license, contributing guide, issue and PR templates.