20260409 / ssh gateways

For your information, incoming modifications:

We are going to apply new security policies on ssh gateways (ssh.psmn and allo-psmn):

These modification will be applied before summer 2026.

See documentation on how to use ssh key pair, ssh-agent, etc: https://www.ens-lyon.fr/PSMN/Documentation/connection/ssh_keys_and_agent.html