feat: wire multi-agent config and routing

Co-authored-by: Mark Pors <1078320+pors@users.noreply.github.com>

scripts/sandbox-common-setup.sh

@@ -59,7 +59,7 @@ EOF
 
 cat <<NOTE
 Built ${TARGET_IMAGE}.
-To use it, set agent.sandbox.docker.image to "${TARGET_IMAGE}" and restart.
+To use it, set agents.defaults.sandbox.docker.image to "${TARGET_IMAGE}" and restart.
 If you want a clean re-create, remove old sandbox containers:
   docker rm -f \$(docker ps -aq --filter label=clawdbot.sandbox=1)
 NOTE