Raise genesis's store as the postgres module's server, so the store step adopts it as it runs (hq issue 609, ADR 0338)

The bundle raised the store as mesh-store, on upstream postgres, in a docker volume; the postgres
module keeps it as postgres, on its pgvector image, in /var/lib/mesh-store owned 999:70, reading its
superuser password from a file. The store step refused, and genesis stopped at step 17 of 24.

The bundle now raises the store with the module's name, image, data directory and password file, and
every step of the bundle and the installer reaches it by that name. The refusal to raise a store over
data it cannot open looks for a cluster in the store's directory, no longer for the old volume.

examples/bundle_test.go

@@ -49,7 +49,7 @@ func TestTheBundleCarriesTheFoundationAndTheControlPlaneAndNothingElse(t *testin
 	}
 	sort.Strings(images)
 
-	want := []string{"mesh-controller", "nats", "postgres"}
+	want := []string{"mesh-controller", "nats", "pgvector"}
 	if strings.Join(images, ",") != strings.Join(want, ",") {
 		t.Fatalf("the bundle carries %v; expected exactly %v.\n\n"+
 			"Adding one is a change to what every first node becomes, and to ADR 0006's "+