feat(supervise): provision agent-side MCP config so Claude sees the sidecar

The supervise sidecar (PRD 0013) has been serving MCP at
http://supervise:9100/ since it landed, but the in-bottle Claude
Code had no `.mcp.json` or settings pointing there — so the agent
couldn't actually call cred-proxy-block / pipelock-block /
capability-block as tools. To exercise the flow you had to curl
the sidecar from a sibling container.

This closes that last mile.

- claude_bottle/backend/docker/provision/supervise.py (new):
  provision_supervise(plan, target) writes
  ~/.claude/settings.json into the running agent container with an
  mcpServers.supervise entry of type http pointing at the
  per-bottle sidecar. No-op when bottle.supervise is False.
- BottleBackend.provision orchestrator gains provision_supervise as
  the last step (after CA, prompt, skills, git, cred-proxy). Default
  impl is a no-op so non-Docker backends aren't forced to implement it.
- DockerBottleBackend wires it through to the new module.
- Test covers the rendered settings shape so a future regression in
  the MCP entry format would surface in unit-level CI.

To test the full flow end-to-end now:
  ./cli.py start <agent> --cwd       # agent's claude sees supervise
  # agent calls cred-proxy-block via MCP
  ./cli.py dashboard                  # approve
  ./cli.py resume <identity>          # restart with new capabilities

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

claude_bottle/backend/docker/backend.py

@@ -31,6 +31,7 @@ from .provision import cred_proxy as _cred_proxy
 from .provision import git as _git
 from .provision import prompt as _prompt
 from .provision import skills as _skills
+from .provision import supervise as _supervise_prov
 from .supervise import DockerSupervise
 
 
@@ -83,6 +84,9 @@ class DockerBottleBackend(BottleBackend["DockerBottlePlan", "DockerBottleCleanup
     def provision_cred_proxy(self, plan: DockerBottlePlan, target: str) -> None:
         _cred_proxy.provision_cred_proxy(plan, target)
 
+    def provision_supervise(self, plan: DockerBottlePlan, target: str) -> None:
+        _supervise_prov.provision_supervise(plan, target)
+
     def prepare_cleanup(self) -> DockerBottleCleanupPlan:
         return _cleanup.prepare_cleanup()