fix(lint): remove unused BottleImages imports from two test files

pyright strict reportUnusedImport flagged BottleImages in
test_docker_launch_committed_image.py and test_macos_container_launch.py;
neither file references the type by name (they only use the returned
value's attributes).

bot_bottle/backend/smolmachines/launch.py

@@ -52,6 +52,7 @@ from ...bottle_state import (
     git_gate_state_dir,
     read_committed_image,
 )
+from .. import BottleImages
 from . import loopback_alias as _loopback
 from . import sidecar_bundle as _bundle
 from . import smolvm as _smolvm
@@ -79,13 +80,20 @@ _GIT_HTTP_PORT = 9420
 _SUPERVISE_PORT = SUPERVISE_PORT
 
 
+def build_or_load_images(plan: SmolmachinesBottlePlan) -> BottleImages:
+    """Build or resolve the agent smolmachine artifact and sidecar bundle image."""
+    _bundle.ensure_bundle_image()
+    return BottleImages(agent=_agent_from_path(plan), sidecar=_bundle.SIDECAR_BUNDLE_IMAGE)
+
+
 @contextmanager
 def launch(
     plan: SmolmachinesBottlePlan,
+    images: BottleImages,
     *,
     provision: Callable[[SmolmachinesBottlePlan, "SmolmachinesBottle"], str | None],
 ) -> Generator[SmolmachinesBottle, None, None]:
-    """Build + run the bottle and yield a handle; tear everything
+    """Run the bottle from pre-built images and yield a handle; tear everything
     down on exit. Errors during bringup unwind any partial state
     via the ExitStack."""
     stack = ExitStack()
@@ -96,9 +104,7 @@ def launch(
         plan = _start_bundle(plan, network, proxy_host, stack)
         plan = _discover_urls(plan, proxy_host)
 
-        agent_from_path = _agent_from_path(plan)
-
-        _launch_vm(plan, agent_from_path, proxy_host, stack)
+        _launch_vm(plan, Path(images.agent), proxy_host, stack)
         _init_vm(plan)
 
         bottle = SmolmachinesBottle(
@@ -184,7 +190,6 @@ def _start_bundle(
     plan = _provision_git_gate_keys(plan)
     bundle_spec = _bundle_launch_spec(plan, network, proxy_host)
     token_env = _resolve_token_env(plan, dict(os.environ))
-    _bundle.ensure_bundle_image(bundle_spec.image)
     _bundle.start_bundle(bundle_spec, env={**os.environ, **token_env})
     stack.callback(_bundle.stop_bundle, plan.slug)
     return plan