All ssh spawns (the -G config probe, the ssh-config:resolve IPC, SSH
terminals, and SshConnection) now go through one pure resolver:
desktop.ssh_path in config.yaml, then System32 OpenSSH, then Git for
Windows' usr\bin\ssh.exe, then bare ssh. Non-Windows keeps bare ssh.
A failed local ssh -G probe is now tagged terminal: boot latches on the
failure overlay (naming the client and the ssh_path setting) instead of
re-driving the same probe every ~2s.
Fixes#103288
a35f600b8a