Port postgres to Go and install the extensions a consumer asks for

letta crash-loops on 'type "vector" does not exist': pgvector is not a
trusted extension, so only the provider's superuser can create it, and
the provisioner never did. A contribution may now name extensions; the
provider creates each (IF NOT EXISTS, available ones only) in the
consumer's database on every pass. Go per the standing rule for a
TypeScript module that changes. letta asks for vector.

modules/postgres/module.json

@@ -109,16 +109,12 @@
       {
         "name": "code",
         "kind": "bundle",
-        "language": "typescript",
-        "entrypoints": [
-          "index.js",
-          "tools/index.js",
-          "provisioner/index.js"
-        ],
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/postgres-provider",
+        "binary": "postgres-provider",
         "loads": [
-          "index.js",
-          "tools/index.js",
-          "provisioner/index.js"
+          "postgres-provider"
         ],
         "env": {
           "MESH_PROVISION_POSTGRES": "postgres://postgres@127.0.0.1:${port:5432}/postgres?sslmode=disable",