Name the one genesis bundle in every bed and the README (hq issue 146, ADR 0331)

mesh-host now carries one genesis bundle, foundation-first-node.lock, on the bus the
mesh runs on; the NATS one it replaces is deleted. Beds that still named it would point
at a file that is gone, and the harness's rewrite for the previous broker's image
rewrote nothing.

test/integration/harness.ts

@@ -23,14 +23,14 @@ import { mustBeHandedOver, pinnedInto, referenceFor, repositoryOf, type HeldImag
 /**
  * The example bundle in mesh-host names a registry that no longer exists.
  *
- * `examples/foundation-first-node-nats.lock` was written **for a target**, and the target was the lab: it
+ * `examples/foundation-first-node.lock` was written **for a target**, and the target was the lab: it
  * pins `192.0.2.250:5000/…` because that is where the registry the lab used to raise served from.
  * That registry is gone, so those three references name nothing.
  *
- * Two of them are ordinary third-party images and belong to the internet. Rather than invent
- * digests here, they are the ones the mesh's own modules already pin — mesh-catalog's `postgres`
- * and `lavinmq` — so the foundation's store and broker are literally the images the mesh runs. The
- * third, mesh-controller, exists in no registry at all and becomes the ID the machine holds it under.
+ * Two of them are ordinary third-party images and belong to the internet. The store's is the one
+ * mesh-catalog's `postgres` module already pins, so the foundation's store is literally the image the
+ * mesh runs; the bus's is below. The third, mesh-controller, exists in no registry at all and becomes
+ * the ID the machine holds it under.
  *
  * **The bundle itself should be fixed in mesh-host**, and this substitution deleted with it. It is
  * here because the file lives in another repository and because a fixture that lies about where an
@@ -38,11 +38,9 @@ import { mustBeHandedOver, pinnedInto, referenceFor, repositoryOf, type HeldImag
  */
 const UPSTREAM_STORE =
   "postgres@sha256:7456ef82e5f5bc43d997f4781bbd7c0d6389bff397564649a356e206ba473aee";
-const UPSTREAM_BROKER =
-  "cloudamqp/lavinmq@sha256:3eb54c12916d700a978c2ea86e6362cd4974b0e3189508718006d4e6d341246b";
 /**
- * And the bus, for `foundation-first-node-nats.lock` — the bundle the mesh raises since it stopped
- * speaking AMQP (novox/hq ADR 0131). The digest is the bundle's own: what the registry served was a
+ * And the bus, for `foundation-first-node.lock` — the one genesis bundle, which raises the bus the
+ * mesh runs on since it stopped speaking AMQP (novox/hq ADR 0131, ADR 0331). The digest is the bundle's own: what the registry served was a
  * copy of the upstream image, so the same digest resolves on Docker Hub, and this is a prefix being
  * removed rather than a reference being replaced.
  */
@@ -59,8 +57,6 @@ const UPSTREAM_BUS =
 export function foundationBundle(path: string, held: HeldImage[]): string {
   let text = readFileSync(path, "utf8");
   text = text.replaceAll(/[A-Za-z0-9_.:-]+\/postgres@sha256:[0-9a-f]{64}/g, UPSTREAM_STORE);
-  text = text.replaceAll(
-    /[A-Za-z0-9_.:-]+\/cloudamqp\/lavinmq@sha256:[0-9a-f]{64}/g, UPSTREAM_BROKER);
   text = text.replaceAll(/[A-Za-z0-9_.:-]+:[0-9]+\/nats@sha256:[0-9a-f]{64}/g, UPSTREAM_BUS);
   return pinnedInto(text, held);
 }