fix(ssh): make agent.sock symlink concurrent-connection-safe

Previously every new login retargeted ~/.ssh/agent.sock to its own
per-connection forwarded socket. That broke a multi-connection setup
when the most-recent connection (which 'won' the symlink) dropped:
all surviving connections' panes would point at a dead socket until a
fresh login from a surviving connection re-ran zprofile.

zprofile: only retarget when the existing symlink target is dead
(sshd unlinks the per-connection socket on disconnect, so [[ -S ]] on
the resolved path is a reliable liveness probe). First connection
seeds the symlink, subsequent logins keep using it.

ssh-agent-refresh: scan /tmp/ssh-*/agent.* for any live forwarded
socket and retarget to the first that responds to ssh-add. Lets the
surviving connection recover without waiting for a new login shell.

0 files changed, 0 insertions, 0 deletions