Add e2e/ dir with Robot Framework tests for page loading, ban records,
blocklist import, config edit. Add requirements.txt. Update Makefile with
test commands. Update .gitignore, backend docs, testing requirements docs.
- Add GitHub Actions CI pipeline with pytest, ruff, mypy
- Expand Tasks.md with implementation tracking and testing criteria
- Update CONTRIBUTING.md with CI requirements
- Add Testing-Requirements.md with coverage thresholds and PR checks
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>