fix(smolmachines): agent dials bundle via host loopback ports, not docker bridge IP

Claude hung on outbound network calls under
CLAUDE_BOTTLE_BACKEND=smolmachines:

  Unable to connect to API (FailedToOpenSocket)

Root cause: the PRD-0023 design pinned the bundle at a docker
bridge IP (192.168.X.2) and set the smolvm guest's TSI allowlist
to `<bundle-ip>/32`. On native Linux this works — host shares
the docker bridge's network namespace, TSI's syscall
impersonation reaches the bridge IP directly. On Docker Desktop
(macOS), the daemon runs in its own Linux VM and docker bridge
IPs aren't reachable from macOS networking, so the smolvm
guest's TSI requests die "Network is unreachable" before they
hit pipelock.

Fix: publish each agent-facing bundle daemon's port on host
loopback (-p 127.0.0.1::PORT), discover the random host-side
ports after start, and route the agent through
`127.0.0.1:<host port>` instead of the bridge IP. macOS loopback
is the surface Docker Desktop's gvproxy forwards into the
daemon's VM, so the chain (guest TSI -> macOS loopback ->
daemon VM port-forward -> bundle container) works on both
Docker Desktop and native Linux.

Concrete changes:
- BundleLaunchSpec: add `ports_to_publish` so start_bundle adds
  `-p 127.0.0.1::PORT` for the agent-facing ports (pipelock
  always; git-gate when upstreams declared; supervise when
  enabled). Egress's port stays bundle-internal.
- sidecar_bundle.bundle_host_port(): wrap `docker port <bundle>
  <container_port>/tcp` so launch can look up the random
  host-side mapping after start.
- launch.py: discover the host ports, build URLs of the form
  `http://127.0.0.1:<host port>` / `git://127.0.0.1:<host port>`,
  stamp onto guest_env + new agent_*_url fields on the plan.
- launch.py: TSI allow_cidrs flips to `["127.0.0.1/32"]`. The
  bundle IP is no longer the agent's target.
- prepare.py: stop synthesizing HTTPS_PROXY / GIT_GATE_URL /
  MCP_SUPERVISE_URL at prepare time — launch owns those now
  (the values depend on a port docker hasn't assigned yet).
- provision_git: gate_host from plan.agent_git_gate_host.
- provision_supervise: URL from plan.agent_supervise_url.

End-to-end verified on Docker Desktop / macOS: guest dials
pipelock through TSI, pipelock forwards to api.anthropic.com,
the API responds with 401 (i.e. it received the request).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

claude_bottle/backend/smolmachines/bottle_plan.py

@@ -75,6 +75,17 @@ class SmolmachinesBottlePlan(BottlePlan):
     # None when bottle.supervise is False, matching the docker
     # backend's convention.
     supervise_plan: SupervisePlan | None
+    # Agent-side endpoints. On Docker Desktop the docker bridge
+    # IPs aren't reachable from the smolvm guest (TSI uses macOS
+    # networking; docker container IPs live in the daemon's VM),
+    # so the agent dials the bundle via host loopback +
+    # docker-published random ports. Empty at prepare time;
+    # launch populates these after bundle bringup via
+    # `dataclasses.replace`. Format: a `host:port` for git-gate
+    # (insteadOf URL prefix) + full URLs for proxy / supervise.
+    agent_proxy_url: str = ""
+    agent_git_gate_host: str = ""
+    agent_supervise_url: str = ""
 
     def print(self, *, remote_control: bool) -> None:
         """Compact y/N preflight. Same shape as the Docker