A definition names no host path for its own data

Twenty-eight modules' data directories are placed: the root as place ".", a sub-directory named by
its id, and every host-side reference — binds, secrets, own secrets, grants, receives, file paths,
mounts, env-files — as ${dir:<id>}. Resolved on the default root every path is the one the manifest
named before, which the controller's TestPlacedDirectoriesKeepTheirPaths proves over both checkouts;
so no data moves and no machine sees a change. Five directories whose id is not their last segment
keep their path as a placement (novox/hq issue 119, ADR 0112, design 27).

modules/builder/module.json

@@ -33,7 +33,6 @@
     {
       "id": "workspace",
       "type": "directory",
-      "path": "/var/lib/builder/workspace",
       "mode": "0700"
     },
     {
@@ -41,7 +40,7 @@
       "type": "file",
       "path": "/var/lib/mesh/builder/builder.env",
       "mode": "0600",
-      "content": "MESH_BROKER_FILE=/run/mesh/broker\nMESH_NODE=${machine:name}\nMESH_REGISTRY=${bound:artifact-store:at}:${bound:artifact-store:port}\nMESH_PACKAGE_BINDING=/run/mesh/package-registry.json\nMESH_NPM_TOKEN_FILE=/run/mesh/package-registry.secret\nMESH_WORKSPACE=/var/lib/builder/workspace\n"
+      "content": "MESH_BROKER_FILE=/run/mesh/broker\nMESH_NODE=${machine:name}\nMESH_REGISTRY=${bound:artifact-store:at}:${bound:artifact-store:port}\nMESH_PACKAGE_BINDING=/run/mesh/package-registry.json\nMESH_NPM_TOKEN_FILE=/run/mesh/package-registry.secret\nMESH_WORKSPACE=${dir:workspace}\n"
     },
     {
       "id": "server",
@@ -53,7 +52,7 @@
       ],
       "volumes": [
         "/var/lib/mesh/builder:/run/mesh:ro",
-        "/var/lib/builder/workspace:/var/lib/builder/workspace",
+        "${dir:workspace}:${dir:workspace}",
         "/var/run/docker.sock:/var/run/docker.sock"
       ],
       "restart-on": [