- Replace Path.write_text() with tempfile.NamedTemporaryFile + os.replace()
in _write_conf_file() and _create_conf_file()
- Ensures atomic operations on same filesystem (temp file in target.parent)
- Prevents config corruption if process is killed mid-write
- Follows existing pattern in jail_config_service.py
- Add proper cleanup of temp files on error with contextlib.suppress()
- Document atomic file write conventions in Backend-Development.md
This prevents fail2ban config files (especially jail.d/*.conf) from being
left in a truncated or corrupt state, which could disable active protection.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
