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/provision/git.py

@@ -28,7 +28,6 @@ from pathlib import Path
 
 from ....git_gate import git_gate_render_gitconfig
 from ....log import info
-from ...docker.git_gate import GIT_GATE_PORT
 from .. import smolvm as _smolvm
 from ..bottle_plan import SmolmachinesBottlePlan
 
@@ -79,10 +78,12 @@ def _provision_git_gate_config(plan: SmolmachinesBottlePlan, target: str) -> Non
     if not bottle.git:
         return
 
-    # IP-literal form: the TSI allowlist passes <bundle_ip>/32 and
-    # nothing else, so the agent has to dial the gate by IP+port.
-    gate_host = f"{plan.bundle_ip}:{GIT_GATE_PORT}"
-    content = git_gate_render_gitconfig(bottle.git, gate_host)
+    # `127.0.0.1:<host port>` form: the bundle's git-gate port
+    # is published on host loopback at launch time so the
+    # smolvm guest (which can only reach macOS networking via
+    # TSI, not the docker bridge IP) can dial it. launch.py
+    # populates `plan.agent_git_gate_host` after bundle bringup.
+    content = git_gate_render_gitconfig(bottle.git, plan.agent_git_gate_host)
 
     guest_gitconfig = f"{_guest_home()}/.gitconfig"
     # Stage the file under the plan's stage_dir so `machine cp`