Feature: Add base configuration example for Docker trusted-proxy deployments

[nickytonline]

Summary

Add a base configuration file example for Docker deployments using trusted-proxy authentication mode. This will help users get started quickly with Pomerium.

Blocked by: #1710 (Add trusted-proxy authentication mode to OpenClaw)

• This feature requires the trusted-proxy auth mode to be merged first

Update base configuration with:

{
  "meta": {
    "lastTouchedVersion": "2026.2.3"
  },
  "agents": {
    "defaults": {
      "model": {
        "primary": "anthropic/claude-opus-4-5"
      },
      "workspace": "/claw/workspace"
    }
  },
  "gateway": {
    "port": 18789,
    "mode": "local",
    "bind": "lan",
    "auth": {
      "mode": "trusted-proxy",
      "trustedProxy": {
        "userHeader": "X-Pomerium-Claim-Email"
      }
    },
    "trustedProxies": [],
    "controlUi": {
      "allowedOrigins": []
    }
  }
}