Update docs and copyright headers

Author: vyruss

docs/changelog.md

@@ -0,0 +1,15 @@
+# Changelog
+
+All notable changes to the pgEdge radar project will be
+documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/),
+and this project adheres to
+[Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.1.0] - 2025-12-18
+
+### Added
+- Initial release
+- Static binaries for Linux (amd64, arm64) and macOS (amd64, arm64)
+- Comprehensive system and PostgreSQL metrics collection