feat: hook mediator daemon into sandbox entrypoint

[zaristei]

Summary

Adds mediator daemon startup to nemoclaw-start.sh. If /sandbox/mediator-daemon exists in the container, the entrypoint starts it as a background process before the gateway, exports MEDIATOR_SOCKET and MEDIATOR_TOKEN to the sandbox user's environment.

This is the NemoClaw-side integration for the mediator policy engine built in OpenShell. The mediator enables per-process resource isolation inside the sandbox — the agent proposes scoped policies at runtime instead of the operator widening the entire sandbox's permissions.

Design doc: mediator-design-principles.md

Changes

• New start_mediator_daemon() function in nemoclaw-start.sh
• Starts /sandbox/mediator-daemon if present, waits for socket, exports env vars
• Writes MEDIATOR_SOCKET and MEDIATOR_TOKEN to .bashrc and .profile for interactive sessions
• Hooked into both root and non-root entrypoint paths
• Fully backward compatible — gracefully skips if the daemon binary isn't present

Test plan

• Verified mediator daemon starts and serves inside sandbox
• mediator-cli ps and policy_list work from sandbox shell
• Existing NemoClaw onboard + gateway startup unaffected when binary absent

🤖 Generated with Claude Code

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: c52e496b-728d-420f-b455-c87359c10d01

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}