v0.8.2

Fixed

• SftpPath could not be imported or used with an asyncssh-only install
  (no paramiko). uri/schemes/sftp/__init__.py imported ._paramiko
  eagerly at module load, and _asyncssh.py imported the
  _DEFAULT_SSH_CONFIG sentinel from ._paramiko, so merely importing
  SftpPath (or the AsyncsshSftpBackend) required paramiko even when the
  caller only wanted the asyncssh backend from the sftp-async extra. The
  paramiko-free bits (the sentinel + config-path normalization) moved to a new
  _sshconfig module, and the paramiko SftpBackend is now imported lazily
  (via _probe_paramiko, mirroring _probe_asyncssh) only when actually
  selected. SftpBackend/_DEFAULT_SSH_CONFIG remain importable from the
  scheme package (PEP 562 __getattr__) for backward compatibility.
  PATHLIB_NEXT_SFTP_BACKEND=paramiko (or auto with neither library) now
  raises a clear ImportError naming the missing extra instead of a bare
  ModuleNotFoundError at import time. Regression test added
  (test_sftp_scheme_imports_and_resolves_without_paramiko, runs in a
  paramiko-masked subprocess).

Full Changelog: v0.8.1...v0.8.2