Reinforce OpenClaw gateway daemon reliability

[webup]

What

Add a ClawMaster-side watchdog so the OpenClaw gateway is monitored and restarted when it unexpectedly stops.

Why

Users report intermittent OpenClaw gateway crashes. ClawMaster should safeguard the gateway in service/CLI mode and make this capability visible in status surfaces.

How

• Add backend watchdog lifecycle around the gateway.
• Expose watchdog status through gateway/status and CLI status.
• Show the safeguard in the Gateway UI.\n\nPlanned by Codex.

[webup]

I’m taking this. Plan: add a ClawMaster backend watchdog for the OpenClaw gateway, wire CLI/service status so users can see protection is enabled, and surface the safeguard in the Gateway page.