Extract shared backup management contract

rules/patterns/go-database/contract.md

@@ -1,6 +1,6 @@
 # Contract: Database Patterns (Go / MySQL / MariaDB)
 
-Version: 1.1
+Version: 1.4
 
 ## MySQL Transaction Cursor Safety (CRITICAL)
 
@@ -115,6 +115,8 @@ This applies to:
 - Imports, bulk updates, and bulk deletes
 - Admin tools or one-off operator commands
 
+Backup naming, storage, archive format, retention, and restore-readiness must follow the `backup-management` contract.
+
 Rules:
 - No schema change or data mutation is allowed on a non-ephemeral database without a current backup.
 - "Small" or "safe" changes are not exceptions.