ssh-gate was built for non-git SSH (PRD 0007), but every
upstream currently declared in any bottle is a git remote, and
those now flow through git-gate (PRD 0008) with credential
isolation, gitleaks scanning, and `insteadOf` URL rewrites.
ssh-gate is left doing L4 forwarding with no gating value over
git-gate's path; carrying it means a redundant sidecar lifecycle,
a shadow-route validator between bottle.ssh and bottle.git, and
a third place to keep an SSH identity in sync.
Goal is straightforward deletion: bottle.ssh becomes a parse
error pointing at bottle.git, the SshEntry / SSHGate / socat
provisioner / pipelock allowlist branch all go away, and PRD
0007 carries a "Superseded by PRD 0009" header so the rationale
of the prior design stays in the tree.
