The builder runs on the machine's network: it copies images into the mesh's registry itself now

The copy between registries (ADR 0096) reaches the mesh's registry over HTTP from
inside the builder's container, where loopback on the default bridge is not the
machine; docker push never noticed because it went through the machine's daemon.
The builder already holds the runtime's socket, so the host network adds nothing
it did not have.

modules/builder/module.json

@@ -64,7 +64,8 @@
         "builder-env",
         "package-binding",
         "needs-npm-password"
-      ]
+      ],
+      "network": "host"
     }
   ]
 }