Remove files that should never have been at the root: a stale litellm-1.79.1
sdist under dist/ (now gitignored), qa_sticky_session.sh which leaked in with
an unrelated commit, and the dead flake8 toolchain (.flake8 plus the dev
dependency; ruff replaced it and nothing invokes it), along with the unused
[tool.isort] section in pyproject.toml
Fold ruff.toml into pyproject.toml [tool.ruff], move codecov.yaml to .github/
and prometheus.yml to docker/, and merge the two divergent license_cache.json
copies into tests/code_coverage_tests/ with the cache path resolved relative
to check_licenses.py instead of the CWD, which is what created the duplicate
in the first place
