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_plan_print_parity.py

@@ -20,7 +20,7 @@ from bot_bottle.backend.smolmachines.bottle_plan import SmolmachinesBottlePlan
 from bot_bottle.egress import EgressPlan, EgressRoute
 from bot_bottle.git_gate import GitGatePlan, GitGateUpstream
 from bot_bottle.manifest import Manifest
-from bot_bottle.workspace import workspace_plan
+# from bot_bottle.workspace import workspace_plan
 
 
 def _manifest() -> Manifest:
@@ -100,15 +100,10 @@ def _docker_plan(spec: BottleSpec, tmp: str) -> DockerBottlePlan:
         egress_plan=_egress_plan(tmp),
         supervise_plan=None,
         agent_provision=_agent_provision(),
-        workspace_plan=workspace_plan(spec, guest_home="/home/node"),
         slug="test-00001",
         container_name="bot-bottle-test-00001",
-        container_name_pinned=False,
         image="bot-bottle-claude:latest",
-        derived_image="",
-        agent_image="bot-bottle-claude:latest",
         dockerfile_path="",
-        env_file=stage / "env",
         forwarded_env={},
         prompt_file=stage / "prompt.txt",
         use_runsc=False,
@@ -124,7 +119,6 @@ def _smolmachines_plan(spec: BottleSpec, tmp: str) -> SmolmachinesBottlePlan:
         egress_plan=_egress_plan(tmp),
         supervise_plan=None,
         agent_provision=_agent_provision(),
-        workspace_plan=workspace_plan(spec, guest_home="/home/node"),
         slug="test-00001",
         bundle_subnet="10.99.0.0/24",
         bundle_gateway="10.99.0.1",