fix: add missing fields to Legacy UniversalClient + bump version to 5.0.56 + concurrency docs

devops/ARCHITECTURE.md

@@ -108,6 +108,23 @@ resource "nubes_postgres_restart" "restart1" {
   run_id      = "2026-02-20-001"
 }
 
+## Concurrency and State Locking
+
+**Provider-level guarantees:**
+- The provider does NOT implement distributed locking for instance operations.
+- Two concurrent `terraform apply` with the same `resource_name` may create duplicate
+  instances, leading to a «multiple instances found» error on subsequent applies.
+
+**User responsibility:**
+- Use Terraform backend with state locking (S3+DynamoDB, etc.).
+- Do NOT run `terraform apply` from two workspaces against the same state simultaneously.
+- If duplicates occur: delete extras via Cloud Console and re-apply.
+
+**API-side limitations:**
+- Nubes API does not enforce unique `displayName` per serviceId.
+- The provider cannot atomically guarantee «create-or-adopt» without API support
+  for conditional creation or name uniqueness constraints.
+
 ## Documentation Model
 
 From the unified YAML, generate: