When the gateway runs inside a Docker container, it needs to connect
to sandbox browser containers via the host network. Chrome's CDP
HTTP endpoints reject non-IP Host headers, so this change:
1. Adds `cdpHost` config option (default: "127.0.0.1")
2. Adds DNS resolution helper to convert hostnames to IPs
3. Updates sandbox browser entrypoint with --remote-allow-origins=*
For Docker deployments, set `cdpHost: "host.docker.internal"` and
the gateway will resolve it to the host's IP for Chrome compatibility.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
