Provisions ~/.ssh/id_ed25519 once and stores it in the FreeIPA KRA
vault so the key persists across reinstalls/new machines instead of
being regenerated each time. Guards against silently overwriting an
existing vault key on transient failures (missing ~/.ssh, vault-add
errors, ssh-keygen failures) before archiving.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>