Add CHANGELOG.md for the Comunity Release milestone (issue 13)

CHANGELOG.md

@@ -0,0 +1,62 @@
+# Changelog
+
+All notable changes to the QuasarApp OpenSimplex2 fork are documented in
+this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
+## [Unreleased]
+
+## [1.0.0] - 2026-10-13
+
+First "Comunity Release" (milestone [#1](https://github.com/QuasarApp/OpenSimplex2/milestone/1))
+of the QuasarApp community fork of
+[KdotJPG/OpenSimplex2](https://github.com/KdotJPG/OpenSimplex2).
+
+### Added
+
+- GitHub Actions CI (`.github/workflows/ci.yml`): builds the project with
+  CMake + Ninja and runs the `test` target (deployed via CQtDeployer) on
+  Linux and Windows for every pull request
+  ([#7](https://github.com/QuasarApp/OpenSimplex2/issues/7)).
+- GitHub Pages documentation site
+  ([#12](https://github.com/QuasarApp/OpenSimplex2/issues/12)):
+  - MkDocs with the Material theme and a teal brand palette
+    (`mkdocs.yml`, `docs/overrides/main.css`),
+  - Doxygen API documentation served under `/api/`
+    (`doxygen.conf.in`, `res/doxygen-material.css`),
+  - `deploy-docs.yml` workflow that rebuilds the site on every push to
+    `main` and deploys it to the `gh-pages` branch.
+- This `CHANGELOG.md`
+  ([#13](https://github.com/QuasarApp/OpenSimplex2/issues/13)).
+
+### Changed
+
+- `README.md` rewritten for the fork
+  ([#8](https://github.com/QuasarApp/OpenSimplex2/issues/8)):
+  - fork main points: performance oriented, C implementation only, Rust
+    implementation removed (it was slow and used a 32 bit source),
+    upstream maintainers inactive, wrappers for other languages via
+    Merge Request,
+  - usage examples in C, C++ and CMake (consumer `CMakeLists.txt` using
+    `add_subdirectory()` and the `OpenSimplex2Interface` target), manual
+    build and test target usage,
+  - new License section pointing to the `LICENSE` file,
+  - upstream-only content removed (2020-era changelog entries, renders of
+    noise variants not part of the C build, area-generator note).
+- License changed from CC0 1.0 Universal to the GNU Lesser General Public
+  License v3.0 (LGPL-3.0) with
+  `Copyright (C) 2026 QuasarApp Group DOO`
+  ([#9](https://github.com/QuasarApp/OpenSimplex2/issues/9)). All code
+  added to the repository after this release is licensed under LGPLv3;
+  existing upstream-derived sources are unchanged.
+
+### Removed
+
+- The non-C implementations (Rust, C#, Java, C++) — this fork keeps only
+  the C implementation; done before this release, announced in the
+  rewritten `README.md`.
+- The root `UNLICENSE` file, which contradicted the new LGPLv3 license
+  ([#9](https://github.com/QuasarApp/OpenSimplex2/issues/9)). Note:
+  `hlsl/UNLICENSE` is kept — it marks the existing third-party-derived
+  HLSL code.