v0.3.1

Fixed

• A composite path falls back when SFTP cannot connect. Nothing on the
  path route connected the provider first: pathlib_next dialled SFTP inside
  the operation, so an untrusted host key (HostKeyNotVerifiable) or a
  refused port escaped raw and the next path provider was never tried --
  while run() on the same host fell back. A composite path now calls the
  provider's connect() before dispatch, and SFTP maps asyncssh's connect
  errors the way the SSH leg already did. Most likely to fire since 0.3.0
  started verifying the SFTP host key: any host not yet in known_hosts.
• run() no longer re-dials a declined provider on every call. 0.3.0
  cleared every decline per call, so a dead primary cost a full connect
  attempt (~9 s against a refused port) on each run() while the fallback
  served. A decline now lasts for the generation again, and is re-admitted
  only when no other provider can serve -- which keeps a single-provider
  host from bricking on one transient refusal, for paths as well as run().
• A path refusal with nothing left to try names why ("no path provider
  completed read (...: Host key is not trusted ...)") and keeps the cause.

Full Changelog: v0.3.0...v0.3.1