A bed says what it actually needs to be pointed at

The instructions in every bed named the bundle that raises the predecessor's
broker, so a first attempt ends in a control plane crash-looping on a missing
MESH_BUS_NATS — which reads like a broken lab. They name the bundle that works
now, and the README says the host binary needs SYSTEM=arch, because one built
without it refuses everything with an empty system name.

And the three habits that each cost a run before they were adopted:
MESH_LAB_KEEP to leave the machine standing, MESH_LAB_WARM while iterating,
and rebuilding all three repositories the bed places rather than the one that
changed.

test/integration/runtime-restart-on-config.test.ts

@@ -12,7 +12,7 @@
  * the container was replaced (a new container id) and the config on disk carries the new value.
  * It builds the host from source (no --no-build), because the behaviour under test is the host's.
  *
- *   MESH_LAB_HOST_BINARY=.../mesh-host   MESH_LAB_BUNDLE=.../examples/foundation-first-node.lock
+ *   MESH_LAB_HOST_BINARY=.../mesh-host   MESH_LAB_BUNDLE=.../examples/foundation-first-node-nats.lock
  *   scripts/build-module-runtime.sh grafana builds mesh-runtime-grafana:development, which
  *   scenarios/grafana-node.yml stocks.
  */