refactor(docker): extract provision_skills to mirror the others

Four symmetric provision sub-methods now: provision_prompt,
provision_skills, provision_ssh, provision_git. Each self-gates with
an early return; provision is pure orchestration.

claude_bottle/backend/docker/backend.py

@@ -271,9 +271,7 @@ class DockerBottleBackend(BottleBackend):
         container = target
 
         prompt_path = self.provision_prompt(plan, container)
-        agent = plan.spec.manifest.agents[plan.spec.agent_name]
-        if agent.skills:
-            skills_mod.skills_copy_into(container, list(agent.skills))
+        self.provision_skills(plan, container)
         self.provision_ssh(plan, container)
         self.provision_git(plan, container)
         return prompt_path
@@ -307,6 +305,15 @@ class DockerBottleBackend(BottleBackend):
         agent = plan.spec.manifest.agents[plan.spec.agent_name]
         return in_container_prompt_path if agent.prompt else None
 
+    def provision_skills(self, plan: DockerBottlePlan, container: str) -> None:
+        """Copy each of the agent's named skills from the host's
+        ~/.claude/skills/<name>/ into the container's equivalent path.
+        No-op when the agent has no skills."""
+        agent = plan.spec.manifest.agents[plan.spec.agent_name]
+        if not agent.skills:
+            return
+        skills_mod.skills_copy_into(container, list(agent.skills))
+
     def provision_ssh(self, plan: DockerBottlePlan, container: str) -> None:
         """If the bottle has SSH entries, set up the in-container
         ssh-agent and config so node can authenticate without ever