docs: update changelog (#8)

## Summary
- capture existing project history using Keep a Changelog structure
- document the unreleased provisioning updates to the devcontainer
- add release comparison links for the 0.1.0-alpha.1 tag

## Testing
- not run (documentation change)

Author: mihailfox

CHANGELOG.md

@@ -6,4 +6,26 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ## [Unreleased]
 
-- Initial Git history with installer script, devcontainer tooling, and smoke tests.
+### Added
+- Provisioning helper scripts (`on-create.sh`, `config.sh`, `utils.sh`) to share devcontainer setup logic.
+
+### Changed
+- Make the VS Code launcher exit immediately when remote initialization fails.
+- Align Helix installation with the packaged version and disable ShellCheck quick fixes by default.
+
+### Fixed
+- Resolve the Helix version mismatch that caused repeated downloads in the devcontainer.
+
+## [0.1.0-alpha.1] - 2025-10-10
+
+### Added
+- Initial project scaffolding, licensing, and installer documentation.
+- Devcontainer definition with explainshell stack bootstrap, shared dotfiles, and hardened provisioning.
+- GitHub workflows for smoke tests, ShellCheck, release validation, and contribution guidance.
+- Installer smoke tests exercising the CLI workflow.
+
+### Changed
+- Release automation updated with the permissions required for publishing artifacts.
+
+[Unreleased]: https://github.com/mihailfox/helix-url-handler/compare/v0.1.0-alpha.1...main
+[0.1.0-alpha.1]: https://github.com/mihailfox/helix-url-handler/releases/tag/v0.1.0-alpha.1