1. merge gitea/master into 25-llm-archlinux-package-manager;
2. incorporate master deps: tomlq, pip==25.1, django, fastapi, uvicorn;
3. add requirements.3.13.txt with version-specific mapping;
4. remove generic requirements.txt, pyproject.toml from tracking;
5. fix whl_cache_download to run once after compile, before install;
6. update m.py to use pyproject.common.toml for bootstrap;
