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/step-ca/module.json

@@ -46,9 +46,9 @@
     {
       "id": "home",
       "type": "directory",
-      "path": "/var/lib/step-ca",
       "mode": "0700",
-      "owner": "1000:1000"
+      "owner": "1000:1000",
+      "place": "."
     },
     {
       "id": "config",
@@ -80,7 +80,7 @@
         "DOCKER_STEPCA_INIT_REMOTE_MANAGEMENT": "false"
       },
       "volumes": [
-        "/var/lib/step-ca:/home/step",
+        "${dir:home}:/home/step",
         "/var/lib/mesh/step-ca:/run/mesh:ro"
       ],
       "secrets-in-environment": "the entrypoint honours DOCKER_STEPCA_INIT_PASSWORD_FILE; convertible, awaiting a bed that proves it"