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/postgres/module.json

@@ -42,13 +42,13 @@
     }
   },
   "receives": {
-    "postgres-database": "/var/lib/postgres/grants/mesh.json"
+    "postgres-database": "${dir:grants}/mesh.json"
   },
   "grants": {
-    "postgres-database": "/var/lib/postgres/grants"
+    "postgres-database": "${dir:grants}"
   },
   "own-secrets": {
-    "superuser": "/var/lib/postgres/superuser.secret",
+    "superuser": "${dir:state}/superuser.secret",
     "broker": "/var/lib/mesh/postgres/broker"
   },
   "resources": [
@@ -61,13 +61,12 @@
     {
       "id": "state",
       "type": "directory",
-      "path": "/var/lib/postgres",
-      "mode": "0700"
+      "mode": "0700",
+      "place": "."
     },
     {
       "id": "grants",
       "type": "directory",
-      "path": "/var/lib/postgres/grants",
       "mode": "0700"
     },
     {
@@ -91,7 +90,7 @@
       ],
       "volumes": [
         "/var/lib/mesh-store:/var/lib/postgresql/data",
-        "/var/lib/postgres/superuser.secret:/run/secrets/superuser:ro"
+        "${dir:state}/superuser.secret:/run/secrets/superuser:ro"
       ]
     },
     {
@@ -101,15 +100,15 @@
       "network": "host",
       "volumes": [
         "/var/lib/mesh/postgres/broker:/run/secrets/broker:ro",
-        "/var/lib/postgres/grants:/var/lib/postgres/grants:ro",
-        "/var/lib/postgres/superuser.secret:/run/secrets/superuser:ro"
+        "${dir:grants}:${dir:grants}:ro",
+        "${dir:state}/superuser.secret:/run/secrets/superuser:ro"
       ],
       "env": {
         "MESH_PROVISION_POSTGRES": "postgres://postgres@127.0.0.1:${port:5432}/postgres?sslmode=disable",
         "MESH_PROVISION_POSTGRES_PORT": "${seat:mesh-store:5432}",
         "MESH_PROVISION_PASSWORD_FILE": "/run/secrets/superuser",
         "MESH_BROKER_FILE": "/run/secrets/broker",
-        "MESH_RECEIVES": "/var/lib/postgres/grants/mesh.json"
+        "MESH_RECEIVES": "${dir:grants}/mesh.json"
       },
       "artifact": "runtime"
     }