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/cli/info.py

@@ -31,16 +31,15 @@ def cmd_info(argv: list[str]) -> int:
         f"first line: {prompt_first_line or '(empty)'}"
     )
     info(f"bottle             : {agent.bottle}")
-    if bottle.ssh:
-        for e in bottle.ssh:
+    if bottle.git:
+        for e in bottle.git:
             info(
-                f"  ssh host      : {e.Host} "
-                f"(Hostname={e.Hostname}, User={e.User}, "
-                f"Port={e.Port}, IdentityFile={e.IdentityFile})"
+                f"  git remote    : {e.Name} -> {e.Upstream} "
+                f"(IdentityFile={e.IdentityFile})"
             )
             if e.KnownHostKey:
                 info(f"    KnownHostKey: {e.KnownHostKey}")
     else:
-        info("  ssh hosts     : (none)")
+        info("  git remotes   : (none)")
     print()
     return 0