Add versioning strategy and CI/CD pipeline

- Add semantic versioning section to development plan
- Map sprint milestones to version tags
- Create Gitea Actions CI workflow (lint, typecheck, test, release)
- Add CHANGELOG.md following Keep a Changelog format

CHANGELOG.md

@@ -0,0 +1,36 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+- Project documentation (requirements, technical specification, architecture decisions)
+- Development plan with vertical slice approach
+- CI/CD pipeline configuration
+
+## [0.0.1] - TBD
+
+### Added
+- Initial project scaffolding
+- pyproject.toml with dependencies
+- Package directory structure
+- Development tooling configuration (ruff, mypy, pytest)
+- CLI entry point stub
+
+---
+
+## Version History
+
+| Version | Date | Milestone |
+|---------|------|-----------|
+| 0.1.0 | TBD | MVP Complete |
+| 0.1.0-beta.2 | TBD | First DVT test runs |
+| 0.1.0-beta.1 | TBD | HAL complete |
+| 0.1.0-alpha.3 | TBD | Network ready |
+| 0.1.0-alpha.2 | TBD | Visual demo |
+| 0.1.0-alpha.1 | TBD | Physics engine |
+| 0.0.1 | TBD | Project scaffolding |