PERF(resources): remove CPU limits - keep memory limits only

- CPU throttling prevents app startup, not crashes
- Memory OOM is the real cascading failure cause
- CPU request ensures fair scheduling

postgresql/manifests/cluster.yaml

@@ -21,8 +21,8 @@ spec:
       memory: "256Mi"
       cpu: "30m"
     limits:
-      memory: "512Mi"
-      # cpu: no limit to prevent throttling
+      memory: "384Mi"
+      cpu: "45m"
 
   # PostgreSQL configuration
   postgresql: