chore: comment out workspace + capability_apply, fix circular imports

The recent refactor partially removed workspace planning and
capability-apply logic. This commit finishes the cleanup so the
test suite imports cleanly:

- Comment out workspace_plan field/property on BottlePlan and the
  provision_workspace dispatch.
- Comment out workspace usages in docker.util (build_image_with_cwd),
  smolmachines.provision.workspace, agent_provider.provision_git,
  smolmachines.backend.
- Comment out capability_apply imports in cli.start and cli.supervise;
  add a local CapabilityApplyError placeholder so the supervise CLI
  module still imports.
- Break the bottle_state → backend.docker → backend circular import
  by lazy-loading docker_mod inside bottle_identity, and by moving the
  resolve_common import inside BottleBackend.prepare.
- Delete tests for workspace and capability_apply (unit + integration).
- Update test fixtures to drop removed kwargs (container_name_pinned,
  derived_image, env_file, workspace_plan, agent_image_ref) from
  DockerBottlePlan / SmolmachinesBottlePlan constructors.
- Delete the obsolete test_smolmachines_prepare.py (tested the old
  resolve_plan signature; the shared prepare flow now lives in
  BottleBackend.prepare).
- Adjust test_supervise.py for the new Supervise.prepare signature
  (dockerfile_content arg removed).

925 → 897 tests, all passing.

tests/unit/test_cli_start_settle.py

@@ -29,29 +29,20 @@ class _FakeHomeMixin:
 
 
 class TestCaptureSessionState(_FakeHomeMixin, unittest.TestCase):
+    # snapshot_transcript is commented out (capability_apply is disabled);
+    # capture_claude_session_state now only handles the preserve marker.
     def setUp(self):
         self._setup_fake_home()
-        # Stub the docker-dependent snapshot call so this stays a
-        # unit test. apply_capability_change's integration test
-        # covers the real docker cp path.
-        self._snap_calls: list[str] = []
-        self._orig_snap = start_mod.snapshot_transcript
-        start_mod.snapshot_transcript = lambda identity: (  # type: ignore
-            self._snap_calls.append(identity)
-        )
 
     def tearDown(self):
-        start_mod.snapshot_transcript = self._orig_snap
         self._teardown_fake_home()
 
-    def test_clean_exit_snapshots_but_does_not_mark(self):
+    def test_clean_exit_does_not_mark(self):
         start_mod.capture_claude_session_state("dev-abc", exit_code=0)
-        self.assertEqual(["dev-abc"], self._snap_calls)
         self.assertFalse(bottle_state.is_preserved("dev-abc"))
 
-    def test_crash_snapshots_and_marks(self):
+    def test_crash_marks_preserved(self):
         start_mod.capture_claude_session_state("dev-abc", exit_code=137)
-        self.assertEqual(["dev-abc"], self._snap_calls)
         self.assertTrue(bottle_state.is_preserved("dev-abc"))
 
     def test_ctrl_c_treated_as_crash(self):
@@ -64,7 +55,7 @@ class TestCaptureSessionState(_FakeHomeMixin, unittest.TestCase):
         # Backends without an identity field shouldn't crash this
         # path (the _identity_from_plan helper falls back to "").
         start_mod.capture_claude_session_state("", exit_code=137)
-        self.assertEqual([], self._snap_calls)
+        self.assertFalse(bottle_state.is_preserved(""))
 
 
 class TestSettleState(_FakeHomeMixin, unittest.TestCase):