Structured result of running a remote command. Callers that need to branch
on the exit code or separate the streams should consume this directly; the
convenience execute_command merges the streams for display.
Chunk size used for streaming SFTP transfers. 32 KiB balances throughput
against memory overhead for concurrent transfers. Larger sizes hit
diminishing returns because SFTP’s window management caps effective
pipelining anyway.
Preferred host-key algorithms advertised to the server, ordered from most to
least preferred. RSA variants (including the legacy ssh-rsa / SHA-1) are
included so that older servers that only offer RSA host keys are still
reachable. The openssl feature on russh / russh-keys must be enabled
for the RSA entries to have any effect.