docs: README, changelog, contributing, security, deployment, operations, CI

CHANGELOG.md

@@ -0,0 +1,23 @@
+# Changelog
+
+All notable changes to this project will be documented here.
+
+Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
+Versioning follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+---
+
+## [1.0.0] - 2026-05-24
+
+### Added
+
+- Initial release
+- Poll Traefik API for docker-provider routers with Host() rules
+- Filter hostnames to configured DNS zone
+- Create and remove A records via GSS-TSIG authenticated RFC 2136 dynamic DNS update
+- Kerberos authentication using keytab (no passwords, no SSH)
+- State tracking across poll cycles to minimise DNS writes
+- Docker secret support for keytab
+- Configurable via environment variables
+- Debian bookworm-slim base image
+- Runs as nobody