chore(docker): add Docker socket mount for sandbox containers

When running gateway in Docker, it needs access to the Docker socket
to create and manage sandbox browser containers on the host.

Changes:
- Add user: root for Docker socket permissions
- Mount /var/run/docker.sock into gateway container

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -1,6 +1,7 @@
 services:
   moltbot-gateway:
     image: ${CLAWDBOT_IMAGE:-moltbot:local}
+    user: root
     environment:
       HOME: /home/node
       TERM: xterm-256color
@@ -11,6 +12,7 @@ services:
     volumes:
       - ${CLAWDBOT_CONFIG_DIR}:/home/node/.clawdbot
       - ${CLAWDBOT_WORKSPACE_DIR}:/home/node/clawd
+      - /var/run/docker.sock:/var/run/docker.sock
     ports:
       - "${CLAWDBOT_GATEWAY_PORT:-18789}:18789"
       - "${CLAWDBOT_BRIDGE_PORT:-18790}:18790"