Fix group attribute syntax: use correct [group('name')] format

- Change all [group: 'name'] to [group('name')] per Just documentation
- Ensures compatibility with Just 1.21.0 and resolves 'Unknown attribute group' error
- Affects all just-commons files: container, volumes, postgres, mysql, images, registry, core

mysql.just

@@ -246,7 +246,7 @@ mysql-shell service="mysql" compose-file="":
     fi
 
 # Restore MySQL database from backup file
-[group: 'database']
+[group('database')]
 mysql-restore backup_file database service="mysql" compose-file="" backup_path="./backups":
     #!/usr/bin/env bash
     set -euo pipefail