fix: enable pgvector for mem0 plugin

- Add allowedExtensions: ['*'] so roles can CREATE EXTENSION
- Grant superuser to 'memory' role (was createdb/createrole, insufficient)
- Needed for mem0 plugin pgvector backend on agent_memory DB

Unblocks kanban task t_3d94b392

apps/base/customer1/hermes-db/pg-cluster-hermes.yaml

@@ -16,6 +16,8 @@ spec:
     - pgvector
 
   postgresql:
+    allowedExtensions:
+      - "*"
     parameters:
       # pgvector HNSW index memory settings
       maintenance_work_mem: "256MB"
@@ -35,8 +37,7 @@ spec:
       - name: memory
         ensure: present
         login: true
-        createdb: true
+        superuser: true
-        createrole: true
         passwordSecret:
           name: memory-db-credentials