feat(ssh-gate)!: remove ssh-gate sidecar and provisioner (PRD 0009)

Delete claude_bottle/ssh_gate.py, the DockerSSHGate sidecar,
and the provision_ssh provisioner (~/.ssh/config + ssh-agent
wiring). Unwire the gate from the abstract BottleBackend
(provision orchestration drops the ssh step,
_validate_ssh_entries goes away) and from the Docker backend
(prepare/launch lose the `gate` kwarg, bottle_plan drops the
gate_plan field, dry-run JSON drops the ssh_hosts / ssh_gate
keys, y/N preflight drops the ssh-hosts block). cli/info now
prints declared git remotes instead of ssh hosts. pipelock's
docstring picks up the git-gate framing now that there's no
PRD-0007 boundary to call out.

BREAKING (dry-run JSON): the `ssh_hosts` and `ssh_gate` keys
are gone from `start --dry-run --format=json`. Consumers should
read `git_remotes` / `git_gate` instead.

claude_bottle/pipelock.py

@@ -57,9 +57,9 @@ def pipelock_bottle_allowlist(bottle: Bottle) -> list[str]:
 
 def pipelock_effective_allowlist(bottle: Bottle) -> list[str]:
     """Deduplicated union of: baked-in defaults, bottle.egress.allowlist.
-    Sorted for stability. Per PRD 0007, bottle.ssh entries do NOT
-    contribute here — SSH traffic flows through the per-agent ssh-gate
-    sidecar, not pipelock."""
+    Sorted for stability. Git upstreams declared in `bottle.git` do NOT
+    contribute here — git traffic flows through the per-agent git-gate
+    sidecar (PRD 0008), not pipelock."""
     seen: dict[str, None] = {}
     for h in DEFAULT_ALLOWLIST:
         seen.setdefault(h, None)