Add Docker install path for OpenClaw OS

[vishxrad]

Summary

• Add a Docker/Compose setup that runs OpenClaw with the OpenClaw OS plugin preloaded.
• Add an editable docker/openclaw-os.yaml bootstrap config for model, API key, provider, and gateway settings before the container starts.
• Add macOS/Linux and Windows helper scripts for env initialization and matched in-container OpenClaw CLI usage, avoiding host CLI gateway protocol mismatches.
• Document Docker as an alternative install path from the root README.

Testing

• docker compose config
• docker compose --profile tools config
• bash -n docker/docker-entrypoint.sh docker/scripts/init-env.sh docker/scripts/openclaw.sh
• git diff --check
• Staged secret scan for real-looking tokens
• Local smoke test from the extracted Docker setup: docker compose up -d --build, /healthz 200, /plugins/openclawos 200, wrapper CLI os url