- relink README/CHANGELOG/pyproject/SECURITY to git.engelgardt23.ru
- port CI from GitHub Actions to .gitea/workflows (publishes Gitea release via API)
- rename GITHUB_REPO -> REPO; drop GitHub mentions in code/docs/comments
- remove .github (workflow + issue templates); drop made-by lines
Drop 'made by engelgardt' from the startup banner too — author credit stays in README only. Exe now ships the embedded icon (CI uses --icon assets/icon.ico).