docs: add CHANGELOG entry for version 2.2.0

Co-authored-by: IntegerAlex <84370725+IntegerAlex@users.noreply.github.com>

Author: Copilot

CHANGELOG.md

@@ -7,6 +7,23 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [2.2.0] - 2026-03-17
+
+### Added
+- `LOG_LEVEL_DEBUG`, `LOG_LEVEL_INFO`, `LOG_LEVEL_WARNING`, `LOG_LEVEL_ERROR`, and `LOG_LEVEL_CRITICAL` named constants exported from the top-level package, replacing bare integer literals throughout the API.
+- `AsyncLogger.close()` method for an explicit per-instance best-effort flush before discarding an async logger.
+- `CONTRIBUTING.md` with setup, testing, style, and pull-request guidelines (the README linked to this file but it was previously missing).
+
+### Changed
+- `shutdown_async_logging` is now registered with `atexit` so buffered async messages are flushed when the interpreter exits rather than being silently dropped.
+- `shutdown_async_logging()` now drains the queue via a `None` sentinel and waits for the background worker to finish before returning, ensuring pending messages are processed.
+- `AsyncLogger.flush()` and `AsyncLogger.close()` docstrings clarified to accurately describe the best-effort, timing-based nature of the operation.
+- Removed legacy root-level `__init__.py` that shadowed the `kakashi/` package in editable installs.
+- Removed `setup.py`; `pyproject.toml` is now the single canonical build configuration.
+
+### Fixed
+- README license text corrected from MIT to LGPL-2.1, matching the `LICENSE` file and packaging metadata.
+
 ## [0.2.1] - 2026-02-05
 
 ### Changed