Add so-postgres Salt states and integration wiring

Phase 1 of the PostgreSQL central data platform:
- Salt states: init, enabled, disabled, config, ssl, auth, sostatus
- TLS via SO CA-signed certs with postgresql.conf template
- Two-tier auth: postgres superuser + so_postgres application user
- Firewall restricts port 5432 to manager-only (HA-ready)
- Wired into top.sls, pillar/top.sls, allowed_states, firewall
  containers map, docker defaults, CA signing policies, and setup
  scripts for all manager-type roles

salt/docker/defaults.yaml

@@ -237,3 +237,11 @@ docker:
       extra_hosts: []
       extra_env: []
       ulimits: []
+    'so-postgres':
+      final_octet: 89
+      port_bindings:
+        - 0.0.0.0:5432:5432
+      custom_bind_mounts: []
+      extra_hosts: []
+      extra_env: []
+      ulimits: []