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

docs/04_development_plan.md

@@ -555,17 +555,98 @@ dashboard/app.py           → hal/factory.py (Sprint 17, upgraded)
 
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+## Versioning Strategy
+
+### Semantic Versioning
+
+This project follows [Semantic Versioning 2.0.0](https://semver.org/):
+
+```
+MAJOR.MINOR.PATCH[-PRERELEASE]
+
+- MAJOR: Breaking API changes
+- MINOR: New features, backwards compatible
+- PATCH: Bug fixes, backwards compatible
+- PRERELEASE: alpha.N, beta.N, rc.N
+```
+
+### Phase 1 Version Progression
+
+| Sprint | Version Tag | Milestone | Release Type |
+|--------|-------------|-----------|--------------|
+| 1 | `v0.0.1` | Project scaffolding | Internal |
+| 3 | `v0.1.0-alpha.1` | Physics engine working | Pre-release |
+| 4 | `v0.1.0-alpha.2` | Visual demo (dashboard) | Pre-release |
+| 8 | `v0.1.0-alpha.3` | Network ready (TCP server) | Pre-release |
+| 11 | `v0.1.0-beta.1` | HAL complete | Pre-release |
+| 15 | `v0.1.0-beta.2` | First DVT test runs | Pre-release |
+| 17 | `v0.1.0` | **MVP Complete** | Release |
+
+### Tagging Convention
+
+```bash
+# After completing a milestone sprint:
+git tag -a v0.1.0-alpha.1 -m "Physics engine working"
+git push origin v0.1.0-alpha.1
+```
+
+### Version Location
+
+The version is defined in **one place** and read elsewhere:
+
+```
+src/py_dvt_ate/__init__.py:
+    __version__ = "0.1.0-alpha.1"
+
+pyproject.toml:
+    [project]
+    dynamic = ["version"]
+
+    [tool.hatch.version]
+    path = "src/py_dvt_ate/__init__.py"
+```
+
+### CI/CD Pipeline
+
+On every push:
+- Run `ruff check` (linting)
+- Run `mypy` (type checking)
+- Run `pytest` (tests)
+
+On tag push (`v*`):
+- All of the above
+- Build package
+- Create release
+
+### CHANGELOG
+
+Maintain `CHANGELOG.md` following [Keep a Changelog](https://keepachangelog.com/):
+
+```markdown
+## [Unreleased]
+### Added
+- ...
+
+## [0.1.0-alpha.1] - 2025-12-XX
+### Added
+- Physics engine with thermal-electrical coupling
+- LDO DUT model with temperature coefficient
+```
+
+---
+
 ## Milestone Summary
 
-| Sprint | Milestone | What You Can Demo |
-|--------|-----------|-------------------|
-| 3 | Physics Working | Unit tests prove thermal coupling |
-| 4 | **Visual Demo!** | Interactive Streamlit showing physics |
-| 7 | Instruments Done | SCPI simulators respond to commands |
-| 8 | Network Ready | TCP server accepts connections |
-| 11 | HAL Complete | Abstraction layer swappable |
-| 15 | First Test | TempCo characterisation runs |
-| 17 | **MVP Complete** | Full end-to-end workflow |
+| Sprint | Version | Milestone | What You Can Demo |
+|--------|---------|-----------|-------------------|
+| 1 | `v0.0.1` | Scaffolding | Package installs |
+| 3 | `v0.1.0-alpha.1` | Physics Working | Unit tests prove thermal coupling |
+| 4 | `v0.1.0-alpha.2` | **Visual Demo!** | Interactive Streamlit showing physics |
+| 7 | - | Instruments Done | SCPI simulators respond to commands |
+| 8 | `v0.1.0-alpha.3` | Network Ready | TCP server accepts connections |
+| 11 | `v0.1.0-beta.1` | HAL Complete | Abstraction layer swappable |
+| 15 | `v0.1.0-beta.2` | First Test | TempCo characterisation runs |
+| 17 | `v0.1.0` | **MVP Complete** | Full end-to-end workflow |
 
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