[tyrex-vberthier]

Replaces ssh-rs with russh 0.60 in keysas-admin/src-tauri. The old crate has been unmaintained since 2024 (last commit, ~20 stale issues, no roadmap) and was the only blocker keeping the operator desktop on it.

Strict drop-in: same algorithm set, same host-key behaviour, same keysas / Changeme007 defaults, same timeout, same SCP-over-exec upload (no SFTP). Public function names are preserved; call sites in lib.rs and utils.rs just get .await. Error type unifies on anyhow::Result since SshError disappears with the crate.

Tested end-to-end against an OpenSSH 10 sshd: connect_pwd, connect_key, session_exec, and session_upload (with byte-exact sha256sum parity on the uploaded authorized_keys). init_keysas against a real station still needs to be run before merge — I couldn't validate that path locally.

A couple of pre-existing issues surfaced while testing, unrelated to the swap, worth a follow-up:

• The confirmation dialogs in ManageView.vue and DisplaySigningConfig.vue pass { type: 'info' | 'warning' } to tauri-plugin-dialog's confirm(). Tauri 2 renamed that to kind:, so the dialogs silently no-op and the wrapped action never runs. Been broken since the Tauri v1→v2 upgrade.
• The onboarding UI tells users to generate keys with ssh-keygen -m PEM -t ed25519 -f mykey. OpenSSH 10 rejects that combination outright (invalid format). Still works on the stable-distro releases operators are actually on, but won't work on anything bleeding-edge.