docs: populate changelog for v0.3.0 release

CHANGELOG.md

@@ -5,6 +5,39 @@ All notable changes to this project 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
+
+### Added
+
+- Enable mistune 3.x plugins with Confluence rendering
+- Use native Confluence task list macros
+- Add plugin feature tests and markdown showcase
+
+### Changed
+
+- Migrate to mistune 3.x API
+- Replace setuptools with hatchling, adopt uv dependency-groups
+- Migrate to bump-my-version with release helper scripts
+- Rewrite workflows with uv, bump all action versions
+- Add CodeQL analysis and Dependabot config
+- Add pre-commit config with ruff, ty, bandit, osv-scanner
+- Add uv.lock for reproducible installs
+- Update mistune dependency to >=3.2.1
+
+### Fixed
+
+- Resolve all ty type-checker errors
+- Exclude test fixtures from prettier, revert test.md
+- Review feedback — consistent uv version, SHA-pin codeql, --no-edit
+- Apply ruff format, prettier, fix bandit SHA1 warnings
+
+### Documentation
+
+- Document supported mistune plugins
+- Note Confluence limitations for abbr, mark, spoiler
+- Rewrite releasing guide for bump-my-version + helper scripts
+- Require CI and publish checks before proceeding in release process
+
 ## 0.2.1 - 2026-04-16
 
 ### Security