docs: add CHANGELOG (Keep a Changelog format)

Reconstruct release notes for 0.0.5 through 0.3.0 from git history,
including the 0.3.0 breaking rename of OpenGJKSharp to OpenGjk

Author: HanJaeJoon

CHANGELOG.md

@@ -0,0 +1,66 @@
+# 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
+
+- `netstandard2.1` target: the package can now be used from .NET Core 3.0+, Unity 2021.2+, and Mono in addition to .NET 8
+- SourceLink and symbol package (`.snupkg`) for source-level debugging
+
+### Changed
+
+- NuGet publishing now happens only on `v*` release tag push (previously on every push to `main`), with a tag-vs-csproj version check
+
+## [0.3.0] - 2026-07-10
+
+### Changed
+
+- **Breaking:** rename the entry-point class `OpenGJKSharp` to `OpenGjk`. The old name collided with the namespace, so consumers could not reference it without a namespace alias
+- Replace `Console.WriteLine` noise in the library with `Debug.WriteLine`
+- Ship IntelliSense XML documentation with the package
+
+### Added
+
+- Input validation with clear exceptions: null/empty vertex arrays, non-finite (NaN/Infinity) coordinates, negative precision, and `GkPolytope` shape mismatches
+- `ComputeMinimumDistance` overloads for `Vector3[]`/`Vector2[]` that return the distance and the closest point on each body (witness points)
+
+### Fixed
+
+- EPA reporting zero penetration depth when both bodies share their first vertex
+- EPA mis-orienting face normals when a polytope face passes through the origin, which stalled EPA at ~0 penetration depth for sphere-like hulls
+- Missing returns in degenerate witness branches that could produce NaN results
+
+## [0.2.0] - 2026-07-09
+
+### Changed
+
+- Apply modern C# conventions to the model types (public fields to properties)
+- Fix the `_presicion` typo to `_precision`
+
+## [0.1.0] - 2026-07-09
+
+### Added
+
+- EPA (Expanding Polytope Algorithm) ported from upstream openGJK: `ComputeCollisionInformation` returns the penetration depth and contact normal
+- `Vector3` convenience overload and a `ComputeMinimumDistance` overload accepting a `GkSimplex`
+
+### Changed
+
+- NuGet publishing switched from an API key to Trusted Publishing (OIDC)
+
+## [0.0.5] - 2025-03-08
+
+### Added
+
+- Initial release: GJK minimum distance and `HasCollision` for convex polyhedra (`Vector3[]`) and flat polygons (`Vector2[]`)
+
+[Unreleased]: https://github.com/HanJaeJoon/OpenGJKSharp/compare/v0.3.0...HEAD
+[0.3.0]: https://github.com/HanJaeJoon/OpenGJKSharp/compare/v0.2.0...v0.3.0
+[0.2.0]: https://github.com/HanJaeJoon/OpenGJKSharp/compare/v0.1.0...v0.2.0
+[0.1.0]: https://github.com/HanJaeJoon/OpenGJKSharp/compare/v0.0.5...v0.1.0
+[0.0.5]: https://github.com/HanJaeJoon/OpenGJKSharp/releases/tag/v0.0.5