61740cdb6a
Servers that don't offer ed25519 (ecdsa-only or rsa-only gitea instances) would raise "ssh-keyscan returned no ed25519 key" because `-t ed25519` produced no output. Remove the `-t ed25519` restriction: ssh-keyscan now returns all supported key types and the function picks the best available via _KEY_TYPE_PREFERENCE (ed25519 > ecdsa > rsa > first). Also adds four new fetch_host_key tests covering multi-type preference logic and updates the stale "no ed25519 key" assertion.