Phase 3.1: the postgres module adopts mesh-store instead of raising its own

server is now the container the foundation raised — same name (mesh-store),
same env (POSTGRES_PASSWORD/PGDATA), ports (127.0.0.1:5432:5432), volume
(mesh-store-data) and the same pinned upstream postgres image the foundation
runs — so the applier adopts it in place rather than raising a second postgres.
The provisioner is host-networked to reach the loopback store at 127.0.0.1:5432.
The module's own network and bind-mounted data dir are gone; there is one
postgres now, holding the controller's contexts and every module's database.

Issue 051 (WBS 3.1).

Claude-Session: https://claude.ai/code/session_01D6qtiYU3P9jk3pnAXyAFyx

modules/postgres/module.json

@@ -60,56 +60,34 @@
       "path": "/var/lib/postgres/grants",
       "mode": "0700"
     },
-    {
-      "id": "superuser-env",
-      "type": "file",
-      "path": "/var/lib/postgres/superuser.env",
-      "mode": "0600",
-      "content": "POSTGRES_PASSWORD=${secret:superuser}\n"
-    },
-    {
-      "id": "data",
-      "type": "directory",
-      "path": "/services/postgres/db-data",
-      "mode": "0700"
-    },
-    {
-      "id": "net",
-      "type": "network",
-      "name": "postgres"
-    },
     {
       "id": "server",
       "type": "container",
-      "name": "postgres",
+      "name": "mesh-store",
       "image": "postgres@sha256:7456ef82e5f5bc43d997f4781bbd7c0d6389bff397564649a356e206ba473aee",
-      "network": "postgres",
       "env": {
-        "POSTGRES_USER": "postgres",
-        "POSTGRES_DB": "postgres"
+        "POSTGRES_PASSWORD": "bootstrap",
+        "PGDATA": "/var/lib/postgresql/data/pgdata"
       },
-      "env-file": [
-        "/var/lib/postgres/superuser.env"
-      ],
       "ports": [
-        "5432"
+        "5432:5432"
       ],
       "volumes": [
-        "/services/postgres/db-data:/var/lib/postgresql/data"
+        "mesh-store-data:/var/lib/postgresql/data"
       ]
     },
     {
       "id": "runtime",
       "type": "container",
       "name": "mesh-postgres",
-      "network": "postgres",
+      "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"
       ],
       "env": {
-        "MESH_PROVISION_POSTGRES": "postgres://postgres@postgres:5432/postgres?sslmode=disable",
+        "MESH_PROVISION_POSTGRES": "postgres://postgres@127.0.0.1:5432/postgres?sslmode=disable",
         "MESH_PROVISION_PASSWORD_FILE": "/run/secrets/superuser",
         "MESH_BROKER_FILE": "/run/secrets/broker",
         "MESH_RECEIVES": "/var/lib/postgres/grants/mesh.json"