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/assigned-model-usage.test.ts

@@ -22,7 +22,7 @@
  * It needs a host binary and the foundation bundle:
  *
  *   MESH_LAB_HOST_BINARY=.../mesh-host
- *   MESH_LAB_BUNDLE=.../examples/foundation-first-node.lock
+ *   MESH_LAB_BUNDLE=.../examples/foundation-first-node-nats.lock
  *
  * HELPER — stock the two runtimes into the local daemon before the run (some may already be there):
  *   scripts/build-module-runtime.sh postgres     /tmp/postgres.tar