Add simplified PostgreSQL infrastructure role for database services

- Provides PostgreSQL server as shared database infrastructure
- Follows KISS principle with only essential configuration (11 variables vs 45 originally)
- Implements maximum security with Unix socket-only superuser access
- Uses scram-sha-256 authentication for application users
- Includes SystemD security hardening
- Applications manage their own databases/users via this infrastructure
- Production-ready with data checksums and localhost-only access

roles/postgresql/handlers/main.yml

@@ -0,0 +1,18 @@
+---
+# PostgreSQL Role Handlers
+
+- name: reload systemd
+  systemd:
+    daemon_reload: yes
+
+- name: restart postgresql
+  systemd:
+    name: postgresql
+    state: restarted
+  when: postgresql_service_state == "started"
+
+- name: reload postgresql
+  systemd:
+    name: postgresql
+    state: reloaded
+  when: postgresql_service_state == "started"