fix(docker): make host Docker socket opt-in (#4902)

* fix(docker): make host socket compose opt-in

* fix(cookbook): gate container Docker access

* fix(docker): gate socket group setup on opt-in

* fix(cookbook): gate generated docker exec serve commands

* fix(cookbook): narrow generated docker exec forms

docker/host-docker.yml

@@ -0,0 +1,12 @@
+# High-trust host Docker access. Enable only when local Docker-daemon
+# management from Cookbook is required and you accept that raw socket access
+# grants broad control over the host Docker daemon.
+#   COMPOSE_FILE=docker-compose.yml:docker/host-docker.yml
+#   DOCKER_GID=<numeric host Docker group id>
+services:
+  odysseus:
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock
+    group_add: ["${DOCKER_GID:-963}"]
+    environment:
+      - ODYSSEUS_ENABLE_HOST_DOCKER=true