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_contrib_codex_provider.py

@@ -25,7 +25,7 @@ from bot_bottle.egress import EgressPlan
 from bot_bottle.git_gate import GitGatePlan
 from bot_bottle.manifest import Manifest
 from bot_bottle.supervise import SupervisePlan
-from bot_bottle.workspace import workspace_plan
+# from bot_bottle.workspace import workspace_plan
 
 
 _URL = "http://supervise:9100/"
@@ -81,12 +81,8 @@ def _plan(
         stage_dir=Path("/tmp/stage"),
         slug="demo-abc12",
         container_name="bot-bottle-demo-abc12",
-        container_name_pinned=False,
         image="bot-bottle-codex:latest",
-        derived_image="",
-        agent_image="bot-bottle-codex:latest",
         dockerfile_path="",
-        env_file=Path("/tmp/agent.env"),
         forwarded_env={},
         prompt_file=Path("/tmp/state/demo-abc12/agent/prompt.txt"),
         git_gate_plan=GitGatePlan(
@@ -108,7 +104,6 @@ def _plan(
             template="codex", command="codex", prompt_mode="read_prompt_file",
             image="", dockerfile="", guest_home="/home/node", guest_env={},
         ),
-        workspace_plan=workspace_plan(spec, guest_home="/home/node"),
     )