Known issues and brief remediation steps

- urllib3 / urllib3-future conflict
  - Symptom: `No module named 'urllib3.exceptions'` or missing `urllib3.__version__`.
  - Root cause: a `.pth` file or packaging hook from `urllib3-future` may mutate the
    `urllib3` namespace in incompatible ways.
  - Remediation: uninstall `urllib3-future`, reinstall `urllib3`, and re-install
    `niquests` if required. See `docs/ISSUES/urllib3-future.md` for more details.